I experimented with dialing in a John Mayer tone preset not too long ago and even put together a video of me playing with the preset with my strat which gets pretty close to John's "Slow Dancing in a Burning Room" tone. No third party cabinet impulses required. Currently working on v2 of the patch now since a couple of buddies had some excellent advice.
It's a free download on Gumroad, just enter $0 at checkout. :)
Here is the video
Here is the Helix preset!
Let me know how you dig it and hope it helps. :)