Stavros,
Fair dinkum! Reading your post has almost made me like my 50d again! I toured my Flickr account and noticed quite a few photographs taken using the 50d with good image quality. I also noted that none of them were taken in very low light!
Yes, it's a fine camera and the image quality is good however, my copy is consistently appalling in low light. I would consider the maximum useable ISO to be 800 and I would be expecting to use Noise Ninja to address this whilst editing.
Neither the 40d or 50d have video capability with/without firmware upgrades and dust/water resistance is as theoretical as the quoted improvement re ISO handling. The 50d uses software ramping above 3200 (artificial post-capture noise reduction over actual sensor gain amplification - a trick more frequently associated with compact cameras). Both cameras are brilliantly built, both have been exposed to the rigours of the Scottish Highlands handling plenty of rain without so much as a glitch but neither have been treated to drops, knocks, kicks or tantrums.
Sorry to hear you had your 7d stolen - I'm not sure I'd know how I would react to such an insult. The 30d is a cracking camera with great image quality however old.
Sensor-stuffing reached critical mass with the 50d in 2008, a technique avoided by Nikon who, at the time held their prosumer models back to 12mp yet after the release of the Canon 5d mk3 with 22.3mp (full-frame cmos) Nikon released their own full-frame D800 featuring no less than 36.3mp? Hmmmmm. The 550d (and onwards) have absolutely stunning low-light performance but lack the toughness or features of the 40/50/60d.
I guess my motivation to dissuade people from buying the 50d over the 40d is based on VFM (50d still demanding a respectable second-hand resale value over the 40d) and my bitter disappointment (with myself) for believing the hype (and that's nobody else's fault Dave) 15mp v 10mp? Subjective, theoretical hyperbole that annoyed me so much I forgot how many decent photographs I've taken using the 50d.
Try Ken Rockwell's website for an insight into the truth behind how, why and the way we use/purchase DSLR's. He rates the 50d highly, insists on shooting in Jpeg format over RAW, never uses a tripod unless he's taking long night time exposures and happily rips into all the major DSLR manufacturers when they deserve such criticism.
http://www.kenrockwell.com/The Fake Chuck Westfall website is hilarious but quite clearly hyper-critical of nearly all Canon products. Quite a potty-mouth about it too. Again, well worth a visit but only if you want an insight into the mentality of the Canon Corporation. His motto appears to be "I'm sorry to hear that the truth offends you".
http://fakechuckwestfall.wordpress.com/Finally,
http://www.flickr.com/photos/bardick/ where images from the 350d, 40d, 50d and 5d mk2 reside.
Whilst the wife is a wonderful photographer she remains largely uninterested in self-promotion so has a badly-managed flickr account with a few images on it. I hope to add some of her more recent photography for her once I've stopped playing with boats!
Dave