I have no opinion on the matress itself but there are two products that provide both peace of mind and ease of use with regards to the crib. One is the ultimate crib sheet:
http://www.babyride.com/bc-43002.html
It's a flat sheet with elastic bands that snap around the crib rails to keep it in place. When it's time to change the sheet you just unsnap it and put another on. It was great when a diaper leaked or the baby spitup because it's fast/easy to remove and the decorative fitted sheet you'll have is protected from wetness and staining. I found having three was the best bet. One on the crib, one for the quick-change and then a third just in case another change is needed before you have the laundry done. So you can go with the heavier mattress if you wish and not worry about how much it weighs :)
The other thing we had is a sound & movement monitor:
http://www.parentbaby.com/products.php?pid=34
Both my first and second babies had/have reflux and I am happy to be called in by the alarm to go check on them (when it senses no breathing/movement for 20sec). I've been much more confident having them in a crib in their own rooms knowing this product would alert us to any potential problems.
How much do I like these products? I have Mar'04 and Nov'06 boys and up until a month ago they were both in cribs with 3 ultimate crib sheets each as well as their own AngelCare montiors. I really liked that with the A/B switch on the monitor and receiver I was able to have one boy's set to A, the other to B and use any of the receivers to listen for either one.