10G's wouldn't be good for fish specimen. However they make pretty good Nano Reef tanks. So if 10g will be used for fish only, might as well get a larger tank. The gist that he was trying to say is this: (1) for FOWLRs or Fish-involved setups, the bigger the better, (2) You cannot buy puffers, tangs, triggers, groupers, and some angels with a 29G. So your livestock may be limited.
But definitely, FOWLRs is better when tanks are bigger because there are more choices. The smaller the tank for
FOWLR's or fish-involved setups, the narrower your choices. Now, it doesn't mean that when your choices narrow, the quality and beauty disintegrate. There are a lot of amazingly colored specimen for a 29G. You might, however, end up with only 2 or three specimen due to size.
LR is between 1 - 1.5lbs per gallon ideal. What's good about your sized tank is that if later on you decide to have corals and anemone and end up buying coral-copatible lighting, it won't be as expensive as a 4ft tank.
Good luck!