Thinking about this topic, there are a few points worth mentioning:
1. Not everyone hears, or perceives, things the same way. Some of us are more discriminating than others. If you aren't getting the tonal quality you like out of the "Dream Rig" then it probably is not for you. Like Chuckie, I hope you find the gear combination that satisfies your ears and soul.
2. Electronics gear often comes off of the line with defects that are not exposed during the manufacturing, or even the quality control process. Sometimes it takes a bit of time and "burn in" for these defects to begin to show up. That's why Line 6 provides a warranty period, during which time, the device can be repaired or replaced at no cost. Advice: During break-in periods (and even after), have a backup plan (see #5 below)
3. In my opinion, the JT Variax as well as the HD500/x are consumer grade gear, but fun and versatile. The guitars aren't even a pale shadow of something like a Les Paul Custom Shop. The HD500/x's are a bucket full of compromises, and at heart are computers, that will most likely die, or become obsolete in time. It can also be argued that the POD will not match the sound quality of a well crafted, expensive, tube amp, or even higher end modelers, such as those from Kemper, or Fractal Audio. The HD PODS are also A LOT less expensive than the others I've mentioned. If you've got expensive ears, and a wallet that can indulge them, by all means, go for it!
4. The DT Amps, to me, are the high point of the "Dream Rig" in terms of sound, versatility, and quality. However, being high voltage electronics devices, they can be susceptible to heat, electronics failure, and tube wear. These can sometimes fail as well during a performance, as can almost any amp.
5. I only play out with my rig about once a month, and I have had no failures in the last couple of years of gigging with it. That said, I always have a fallback if one of the elements fails. For my JT59, I can fall back to the mags. For the HD500, I can plug my guitar directly into my DT25. For the DT25, I can plug my HD500 directly into the PA system. I keep a set of "Pre" tones for using my DT25, and a set of "Normal" tones for going PA direct. Is this ideal? No, but it will get me through the show. If your performance demands that you have full replacement ability and exact tones for every song during a show, then bring replacements for everything. I would find it hard to believe that high paid professionals don't bring backup gear "just in case"
By the way, I'm not making these points as a "Line 6 Expert," but as a regular guy who likes to play, enjoys the flexibility that the "Dream Rig" offers, and finds the tones to be easily good enough to sit nicely in the band's mix. My $.02 USD