You don't see too many people regret a 8 bulb ATI. Some move away from them for some reasons, but not because they hated them or were unhappy with the performance... some fell for the old "bulb cost" argument or wanted some dusk/dawn apps.
therman uses the Photons. Knowing what it takes to have a TOTM type of tank, take a look at his threads and see if that kind of performance will work for you. This is not some thumb sucker with a few boogers that have just barley encrusted the frag plug who likes to show everybody their success.
If somebody pried my MH away from me, it would be ATI 8 or even 10 bulbs maybe with some RB strips for a bit of shimmer (like MH shimmer, not Kessil shimmer which drives me insane). Then Photons way up high running at 100% on all channels if T5s were not a choice, but I have the room.