The IIIg is a fantastic camera, my favorite Leica so far out of the models I've tried, which are the IIIa, IIIf, IIIg, and M2. It's the perfect balance of compact size and a great viewfinder. That said, I ended up getting a new pair of eyeglasses a few months ago, which left me unable to really see the framelines in the IIIg and have gone back to shooting an M2 primarily. If you were planning to just get one Leica, and eyeglasses don't come into play, I would opt for a IIIg with a collapsible Summicron. It won't be quite pocketable, but it is certainly more compact than your current set-up. However, it sounds like you are looking for a compact alternative to pair with your M3. With that in mind, I would opt for a IIIf with a f/3.5 Elmar. Yes, the viewfinder isn't that of an M or the IIIg, but it is just so compact. It really is pocketable. Plus, you could get that pairing for cheaper than the price of a IIIg body alone.