I'm amazed you're still using a 350D
This is funny because I work with a guy who still uses his 350D and he swears by it. He says a couple of reasons why he still loves it is because 1) The pixel pitch is 7.4um (close to the full frame 5D & 5D2) and produces noise free images all the way through his ISO range and it is a larger body than the newer Rebels and feels "beefier".
I suppose that is a testomony to the quality of Canon's products, that such an "old" DSLR is still going strong, even after years and years of use. Personally? I would have dumped it years ago in favor of the newer, brighter (and larger) LCD back displays. I can't imaging how we got past such a small, dim display and made it work, but compared to film, at least you got something to look at vs. having to wait to develop your film to see...
I completly disagree with the noise in the 350D; the 350D is quite awfull when it comes to noise; but hey, this is an 8year old design. Otherwise I have no quality issues. The eyepiece fell of twice, so I needed replacement. The grip starts to loose its texture, and the screen has scratches (so it is even harder now to really see something); but everything is still working, and it reminds me that the most important part is the photographer. I have to work a little harder, and I have to understand a little better what I'm doing than the other guys with new gear.
My conclusion is, that the equipment is not the most important thing; and yes, upgrading from one consumer camera to the next is a waste of money; wait a few years so that there is a bigger improvement. Upgrading to a semipro or pro camera is also a waste of money, when you are not using the camera often.
The real luxury is not having a 1Dx with 10 L-lenses, no it is having time to make good photgraphs whit any decent camera.