Even Dwarf will get large, maybe not in 46G, almost double the size of FMC. Unless planned to give him new and bigger accomodation soon, I would prefer FMC.
When you convert over to Reef, just becareful whenever you stick your hand into tank as both can comouflage well by on the rock. It could be an very painful experience.
If you are allergic to bee sting or other foods, should stay away from it, for your safety. I would even recommend to wear thick glove when handling LR. I know of grown man ending up in the hospital for few days will inflammation of fingers and arm and incredible pain, possibly caused by unkown sting/cuts he may have received while he was handling uncured rocks.
I dont mean to to scare anyone but there are known snail (which maynot be visible to untrained eyes) which can sting you which will deliver death on humans in matter of seconds. CURED LR tend to be safe, but you never know what might be on the rock.
Both of them are good stalkers but FMC camouflage better. Dwarf wiil come up to the top for food once well conditioned in the tank but I dont recall ever being able to condition FMC to come to top to eat.
Although Dwarf are lot easier to initiate the feeding in captivivity, FMC is not that bad either. Just buy the one that is eating frozen food already (chooped krill/ Prawn/silversides).
Good luck with your new venture!!!