You can always mix and match. I had 3 xr30s, then got two unos, then got the third and swapped the unos to primary position. Im keeping my 30s for when i move to the 8fter i dont have the cost of a used car in front of me for lighting.nah, that wasn't me haha.
i use 2 hydra 32hd's and both have the reefbrite xho kits roughly 12" over the water, over a 3' 40B. i WANT to upgrade to the reefi. might have to sell my hydra's/reefbrite's and buy a reefi. if i have $$ leftover i'll put it towards 2 quanta bars. i'm planning on switching to a 60G cube from this 40B. my GF wants to have more room in the living room, for our dog..so i have to compromise