Floating/Recessed
+ You can pull up, and other cool effects like flutters etc.
- You need to re-set the spring tension if you change tunings
Non Recessed
+ Its easy to down tune, no need to adjust the trem claw.
- No cool effects
- The string bolts/fine tuner spring can eventually damage the finish (Floyds only)
A lot of the pros / cons have been answered. I used to swear by having the Floyd flat to the body...simply because I could change a string so quickly.
However as I was never breaking a string I then tried them floating and I'll never go back....cool vibrato, squeels, effects etc. (however EVH always seemed to do OK!)
So, I've got two Silos with recesses BUT - I used my dads Morse at the weekend which has the bridge set flat......wow, the difference in tone was incredible just very loud accoustically and very thick through the PA - this was offset against no vibrato, effects etc and I'll always have trems that float - but the difference in tone was very noticeable (same as when compared to a fixed bridge Silo etc)