There have been several settings or adventures so cool in the last few years that I've been tempted to drop my current campaign and play them -- including d20 Cthulu, Testament, and Necromancer's Legacy, to name a few off the top of my head. And Grim Tales is such a compelling ruleset I was pretty tempted to hit the reset on my current game and start over.
So far I'm staying the course, since the one time I couldn't resist this impulse was an unmitigated disaster: My very first campaign ever, back in the early eighties. We were running basic D&D, the old Moldvay set, and I think the players had just gone through the Isle of Dread or Castle Amber. The PCs were, maybe, 6th level or so. And then I read D1-2, Descent into the Depths of the Earth, with this super-cool new monster, the drow, which are like, evil underground elves, and I just had to drop everything and run them through this most incredibly amazing module immediately!!!!!!
The result was my first (and hopefully last) TPK. The very first encounter, the drow checkpoint, and the whole party got completely wiped out, within ten minutes or so. My brother and sister and cousins, naturally enough, wanted to know why the hell I though this module was so great.
And so, for the first (and hopefully last) time I used the old "it was all a dream" excuse to reverse history. *Shakes head.* I've never run that module, even though I still think that whole G-D-Q series was the best. module. series. ever.