@Doadman, I understand your concerns, the GT-8 however will allow you to put any effect anywhere in the chain, unlike most MFX's, you wouldn't have a problem with the wah.
Concerning the HC, radley (Hockingsmith) is Neal Diamond's guitar player (more than 20 years now) and inventor of the Harmonic converger, I don't own one of these myself (would love one, can't afford it, around $200 U.S.) and the device does all that it claims, Ive heard clips and read reviews of 2 years and yes..it does impart a "tubelike" sound to the GT-8 and makes "tweaking" the sound for patches less tedious by all accounts.
It is possible to get a
very good sound out of just the preamps in the 8 without using the od/distortion pedal sims.
There are some alternative EQ's and methods posted at GT Central in lue of using the HC, but only an HC will get that particular sound that it is known for, it is after all an analog device and the GT-8 is digital, that isn't to say that you couldn't put a tube driven unit into the loop section to achieve similar results but the HC is truly one of a kind and he makes them to your specs. you can find him here:>
http://bossgtcentral.com/forum/forumdisplay.php?f=152Don't give up on the Tonelab tho unless you're dead certain, many people have been extremely happy with that unit.