Re: modulation pedal
The above named Magic Stomp from Yamaha might be worth checking out, it gets real good reviews allover, so if you have the chance to test one out, give it a spin.
Personaly I think the RP350 from DigiTech does not do a too bad job either, and is not too expensive either. I use the GNX myself, only through the FX-loop's return, skipping the preamp and using amp/cabinet mods, with nice results in my opinion.
Korg's Tonework has the features you named, and although not that bad of a unit, I guess there are better choices out there such as the RP350, which has new DNA2 Processors and a lot new amp/cab models, and very decent effects including Lexicon reverbs, etc...
I would certainly check out a DigiTech RP350, and see if you like it for what you are after.