ok, my disclaimer before i go further. I HATE REFUGIUMS!!
they do not do anything that people think that they do. they are a warm a fuzzy feeling item that people like to add. they are nothing more than another place to do more maintenance on. i feel any open area in a sump should just stay open. it allows all of the detritus to settle out in a nice open area that is easy to siphon. putting stuff in there just hides the detritus allowing it to rot away and raise phosphate levels in the tank. hence the reason why algae grows there. if you were to siphon out this stuff before it rots, than you would not have any algae at all anywhere in the system. is that not what we are looking to accomplish.
one of those things people will go out of there way to save 5min of work which will save them 12 hours of hardship and a crashed tank 3 years down the road.
as of now the ONLY maintenance i do on my tank is a 10g water change a week. that is all. it takes me 10min to do, this includes a thorough siphoning of my sump. the sump is the only place i have to siphon. the display has enough flow in it to keep the detritus in suspension or settled in the sump ready for the next water change.
the rest of the time i am able to do all of the stuff i enjoy about SW aquariums. the fragging of corals the placement of fraged corals and the sitting and watching of the tank.
eventually all
sand beds get full of phosphates and will need to be removed. just the nature of what it does. at some point the refugium will need to be drained and shop vacced out of all substrate in there and started over. i would just rather skip that step.
ok, back to your regularly scheduled non-soapboxed episode of TRT.
i just realized that both of you are new members.
there is more than one way to run a reef tank. i prefer the small every week maintenance version over the very large every three year overhaul version. i have done both over the past 15+ years on this hobby. if you do not plan on keeping this tank setup for more than 2 years, for whatever reason, moving, going to a bigger tank, whatever. than by all means go with a sand bed in both the display and in any other body of attached water. sand beds are a VERY forgiving system. hence the reason everyone tries to push them, but they do have thier drawbacks and they pretty quick after about year 2-3. at this point most people have learned what they did wrong and are looking to upgrade, or will redo the entire tank anyway.
ok, i lied, i promise i am stepping off of the soapbox now.
G~
more closely 
a sand bed system is a lot more forgiving, but you need to be thinking about sand replacement several years down the road. someone just starting out than this could a wise choice. i prolly would recommend this to anybody starting out with a tank smaller than 75g. once you get above 75g sand bed removals get pretty nasty and problematic. 
