ReGenesis have long since moved on from Glynn Protheroe - Tony Patterson has been the band's vocalist for at least 10 years now. Curiously, RG's main website URL isn't working but there is another URL that allows access and it appears the band are taking a break of sorts (they've done this before and then returned). Other UK Genesis (and/or Collins) tribute bands include "G2enesis"; "In The Cage" and "Mama".
On the issue of live recordings, well, Brit Floyd has done exactly that with its DVD and CD and if it's well done I can absolutely see/hear the reason for doing it. I have the DVD and, as stated elsewhere on this forum, the sound reproduction (distinguished from playing style and musical phrasing) is better than the stereo track on Pink Floyd's Pulse - at least to my ears.
The ReGenesis live CDs are patchy. I have the first four but not the latest. Some of it is very good whilst some of it is less convincing. But, nothing so bad that there is any inclination to get rid of any of the CDs. As it is unlikely Genesis will ever perform in anger again, the only real channel open to fans of the music is through tribute bands. Same with Pink Floyd.
One reason why GOOD recordings by tribute bands may well be worth having is when material is performed that either wasn't performed very often by the original band and/or there aren't any (known) quality recordings by the original band of particular material. For example, Pink Floyd's "Animals" appears to be a case in point and, based on the content of the Experience / Immersion releases, it seems reasonable to conclude that there also isn't a complete live performance of "Wish You Were Here" that Floyd feel able to release. In my opinion, the version of "Pigs (3 Different Ones)" on the Brit Floyd DVD is truly excellent and is not dissimilar to the way it was performed by Pink Floyd on the '77 tour (I have a half decent bootleg to make the comparison

). To my knowledge, the only live performance of a song from Animals that has been officially released (excluding tribute bands) is "Dogs" on Roger Waters' "In The Flesh" live CD/DVD. It's possible "Sheep" may eventually appear if RW decides to release a CD/DVD of his Dark Side of the Moon tour. I don't think any "live" material from Animals has ever been officially released under the Pink Floyd banner.