I find a Dremel is great for tight spots. Also produces less heat when slicing into sheet metal (and I'm working on some pretty thin stuff). After using a die grinder, I can knock down welds a little more before using a sanding disc and thus need less use of a sanding disc which can help prevent thinning out the sheet metal too far or reducing heat. I use the Dremel for making thin plunge cuts to get a bodysaw blade into the cut. I still have all the usual tools for grinding down welds like air belt sander, body saw, DA sander, several die grinders, etc. and also have an excellent compressor setup to run them. I don't care what anybody says, I can't see not using my Dremel for some things.
Anyway, I ended up buying a Dremel 4000 model off CL in almost new condition for about the same cost as a new switch. The 4000 is a much better tool for more frequent use. It has a separate on/off switch and speed control switch. The 3000 requires you to move through all 10+ speed settings to get to full speed so if you want full speed every time, it's going to put more wear and tear on the contacts. The more powerful motor is better too.