Upgrading my Schecter Omen Extrem 7 - Worth it?

Depends. What kind of music are you looking to play? I'd throw an EMG 81 in the bridge with the 18V mod and a Liquifire in the neck...
 
DiMarzio pots are just rebranded CTS, I believe.

I wouldn't go for Sperzels, but that's just me. You're going to have to drill holes to install them. They are not a direct replacement for pretty much any other tuner in the market.