Today i sat down for many hours comparing 292 with 370 using the exact same settings, same speakers, same guitar, same phrases with the same 10 different presets (from 292 and settings backup) on both firmwares, eq is OFF of corse. The recodings clearly showed a difference. 370 against 292 produces way more treble (hiss, hsss,sss) which may gives the impression of a somehow "clearer" sound, but makes certain presets sound rather like a behringer vamp then a helix . 292 sounds way warmer to me (slight lower trebble or upper mid boost), the antialiasing is there but not in the way. I do not know what Line 6 did, but 370 sounds definatly worse then 292. Too much sss hsss, shhh, certain presets sound rather flat compared to 292. 370 sounds like the signal goes through a slight final compression with a misaligned exiter. I have no idea when these "changes" have been introduced, so ill stick with 292 for now. Dont really have the nerve to try out 196 different firmwares in order just to sneak a few new effects. For the everage or new user the difference may be not noticable,but when comparing recordings side by side you clearly notice the difference. The difference is less noticable on presets with lots of delay and reverb, but rather on tight dry presets which are supposed to sound clear. 370 seems to overdo it somehow with "fidelity" which you (i) dont really need in the studio. You may try a Strat with a Dire Straits preset in position Pickup 4 then you may know what i am talking about.
When i first tried 370 i immediately had the impression of beeing something not right, now i know for shure. The only positive thing about 370 i could discover soundwise was less antialiasing like descibed IIRC around 350, heights sound cleaner, but there are too many of them unfortunately.