I wish you the best!
I had a similar problem and replaced the 350 with a 40D. The 5D was too expensive and it's also going to be upgraded (six months?). Thing is also, the 5D is full view, so not all lenses work with it. But full view is better for wide-angle (no more multiplying with 1.6) but tele becomes more expensive (same reason).

My opinion on the 40D: it can replace my Olympus OM4, a camera I loved (and still love).Heavier, larger that the 350, yes. But working with it is easier, except for AEB which needs the menu's. Autofocus works better, but manual is still often needed. Preview is much larger, the viewer is a step ahead. It works very fast in RAW. Signal to noise is very good up to 800, and 1600 is better than 350 but visible. NoiseNinja basic (in Bibble) takes care of most of it, and for print it's not a real problem. I shot 6Giga of raw with autofocus but no flash, anf the battery was still indicated as being full. I'll upload some captures soon.
Do take into account that I rarely use all the subtle advantages of digital: I primarily use a camera as a film camera with a sensor instead of film, and the advantage of not having to change film due to sensitivity problems.

There are no Borg. All resistance is fertile.