All reef tanks start out as FOWLR
's and grow into reefs as experience/knowledge grows and money becomes available. The FOWLR
tank is the stepping stone because the tank is outfitted with a LR
aquascape and the corals can then be added from there.
I would start off with the LR
and buy lighting for a reef, that way you won't limit yourself.
One very important thing to remember is.....do it slowly. Don't rush anything, and research like you seem to be planning on. It's a very important step and can be the difference between success and failure. Keeping SW
tanks is not difficult, but it does require lots of knowledge.
I have a 46G tank that is slowly growing into a full reef. You'll be fine with a tank that size for a full reef, but I do like to mention (as did Hara) that your stocking options become slightyl limited when deciding to go with corals and/or a smaller tank.
Try and make a list of what you REALLY want to keep, and formulate your system around that.
A ~40G reef tank won't allow for any tangs or angels (maybe a pygmy if you get lucky, they usually nip at corals).