open-top reef tanks

I wanted to get your thoughts on open-top tanks...

I have a 30 gallon acrylic that I'm thinking about setting up as a
reef tank. When I say "open-top", I mean that there is very little
horizontal acrylic on the top of the tank. (There's only a "brace" in
the center.) My tank was made for a certain hood w/ integrated light
& filter that fits on top. (Imagine the top of Frankenstein's head
sitting on top pf a beautiful woman's face and body...)

The only concerns that I can think of would be excess evaporation and
the possibility of salt deposits on the "rim" of the tank. But on the
plus sude, there would be no acrylic between the lighting and the
water's surface.

Do any of you have preferences one way or the other? Does anyone have
a nice open-top reef tank like the one I'm thinking of?

Your thoughts and advice are appreciated.

Muchos Gracias,
Juan