I won't say I've gone back to 35mm...more that I've never left it. I love MF and LF gear, but sometimes 35mm is the right tool for the job. Sometimes I want rough, grainy images. (For me, early morning fog is the perfect example of where I like the grain to intrude a bit into the image. Not that MF and LF won't give spectacular results on foggy mornings...just that sometimes I'm in the mood for an image with a rough edge and 35mm Tri-X is a great way to get what I want.)
The other thing is that, of course, some situations are just easier to shoot with 35mm. Nobody notices my Contax G1 in a crowd, but you can bet that even my smallest MF camera (a Fuji GA645) attracts attention. And pulling out a Crown Graphic is an open invitation for people to make me the center of attention. So some shots are almost impossible with anything other than 35mm.
I love every format that I shoot, but all for different reasons. I'm fortunate enough to have a collection of equipment that allows me to match the equipment with both the situation I'll be in and the mood I want the picture to create.
An interesting topic...thanks for bringing it up.