I've been there, Gary...
In more ways than one, so I can almost taste both your angst "on the night" along with the salt air.
(I just wish we'd been in touch before your "nightmare" gig.)
I'm hoping Don B, Perry and the Line 6 guys will forgive my "rough and ready outback explanation" of the reasoning that's given rise to my policy for using RF1 vs RF2 frequency schemes.
(Bear in mind that I only have nine receivers, being two racks of four V70's and the sole V75 that provides USB "upgradeability". As a result, the two extra channels that are "missing" from the RF1 scheme are only of academic interest to me.)
Indoor jobs, such as teleconferences, presentations, fund-raisers and the like, generally require shorter RF range, have almost zero marine, rain or other moisture involvement, but are likely to require coexistence with WiFi, hence RF2 for happy camping.
Just about everything else, ...RF1.
Almost invariably, the "everything else" features an abundance of RF-reflective and/or absorbing nuisances, ...trees, rigging and salt water (whether coastal airborne vapour or sweat) being among the worst.
My (probably oversimplified) Aussie understanding of Line 6's XD-V schemes goes like this:
(The "frequency diversity" I'm about to mention in respect of both schemes is in addition to that provided by Line 6's inbuilt "line of sight" diversity switching between antennae.)
RF1 would seem to trample over pretty much all the 2.4GHz ISM band in order to provide each of its 12 channels with an inaudible, instantaneous, rapidly-switched, diversity "choice" between four separate frequencies. That's why it so effectively bullies the other WiFi kids right out of the sandbox to punch its way over the whole playground.
Line 6 have been their usual ingenious, client-based selves in recognising that the majority of users may neither require the maximum range, nor need to rely on the robust RF workarounds that are inherent in their original RF1 offering, but will often require peaceful co-existence with WiFi.
I'm guessing that while they were reorganising spectrum (in developing the RF2 scheme) with a view to leaving some space in the sandbox for the WiFi kids, they figured that not only were four separate frequencies per channel "overkill", but also by reducing their diversity to a choice of (a nonetheless very practical) two, they'd have "created the space" they wanted for WiFi interoperability, with enough left for a very popular pair of extra channels.
Win-win, ...for most users.
Which you and I ain't.
Here's my personal recommendation ...
If you don't need to worry about using wi-fi at the same time, then by all means use RF1. RF2 is an "extra" mode that was invented as a solution for those people needing both wi-fi and XD-V at the same time. What does this mean? Well you can typically run a few XD-V channels AND wi-fi at the same time (in RF1 mode) with a little planning without adversly affecting the wi-fi. First you want to pick your XD-V and wi-fi channels based on the recommendations in the FAQ. Remember wi-fi channel numbers and XD-V numbers do not directly correspond. Now if you can also plan a little about antenna placement vs wap placement this is reasonably easy to achieve.
Wi-fi is constantly getting clobbered. When this happens is slows down. It slows down if you turn on a microwave oven. It slows down if there is a second computer in the room on wi-fi .. let alone if there are a dozen. It slows down when your neighbor in the next building turns on their wi-fi. It is not a good medium for anything mission critical, but people keep using it that way. [/rant]
When you use RF2 mode you are letting some of the XD-v's guard against interference down ... BUT ... you are getting more space (frequencies) available to strategically place them out of harm's way. But you must use a fair amount of care to insure that this happens. You lose some of the plug-and-play mojo that RF1 mode offers.
Should you think there's anything the least bit "over the top" in your "ranting" about inapproriate reliance on the part of whining and whinging WiFi users, Don...
...Be grateful you haven't heard my response to typical complaints from journalists, ...who loudly decree that the uninterrupted and rapid WiFi filing of media is an inalienable right granted them by the Fundamental and Immutable Laws of the Universe.
Nobody actually reads all the shrinkwrapped EULA's that you sign off on ... but at least here in the USA wi-fi and XD-V mics are considered "part 15" devices, along with computers and garage door openers. By using one of these devices you agree to not cause interference to any licensed service, but must accept interference caused by other services.
Wi-fi, being unlicensed, has no standing and must accept interference from anything, so do our wireless mics. We've just developed a scheme that almost always wins.
Just adding to Don's otherwise spot on comments, RF2 was also created to afford the opportunity for 2 additional channels and lower latency. Both of those features are most important in large performance spaces where for the most part the WiFi can either be turned off during performance or is far enough away to be a non-issue. There are many theatre groups out there successfuly using all 14 channels.
You may find this bizarre, Steve...
But I frequently add delay (latency) in large conference venues where the delegates aren't physically close enough to lip-read the person speaking !
This is because it's become fashionable for a gigantic projected (and mind-numbingly boring) image of the keynoter to loom immediately behind and over them, with a few frames of delay inherent in the processing required to remove scanning lines and other artefacts.
It's easy to restore lip-sync with the inbuilt "Single Delay" of my Yamaha EMX5016CF and this additional delay is readily accepted by those on the podium as being "the venue sound", ...if they notice it at all.
Don't for one moment think that this means your great work in reducing latency isn't heartily appreciated !