I don't think either will get messy, but I think to allow more absorbtion of water column nutrients etc, that the use of small grain gravel is preferred over sand. Nothing wrong with sand however, esp if you keep cories & the such like. Many people uproot plants when replanting a setup. I don't believe this is enitirely necessary - just cut them off leaving the roots behind to rot down & provide further nutrients to the substrate.
Which is also what Tropica recommend - I guess it will also reduce the mount of ammonia which may be released from the substrate when you disturb it moving plants around etc.
I'm using black gravel which I regret now =(
wish I chose sand would have looked nicer.. and not looked so bad when It mixes in.. I know it will because I'm clumsy Oh well Can always buy more and do it again one day =)
