It pretty much would depend on what you want to use the SansAmp for... if you're looking to warm up your signal, you probably wont need it. The SVT's preamp is the finest you can find in my opinion. If you're looking for some dirt, yeah the SansAmp will probably work great. I use a GEB-7 to get some midrange punch when I need it and an MXR Bass Distortion for dirt, but otherwise my tone is all SVT.
As for weight, yeah... there's no mistaking that it's a beast. Mine's in a custom Calzone 5-space rack that I customized with wheels so moving it around isn't bad but it's definitely a 2-man lift when it comes time to get it on my cabs.