I guess I'm ready for an upgrade and I want to stick to Canon due to my lenses yet I'm just twiddling my thumbs while the competition looks more appealing with each announcement.
I have a Canon 550D with a Sigma 17-70 F2.8-5.6 and Canon 50mm F1.4
Honestly, I'd be happy with a improved Canon SL1/EOS M with adapter. I don't like bulk since I shoot on the run a lot and don't need many of the features that the higher end models have.
So, what features do you need?
The 550D is a good camera, do you feel you need more resolution? (to what end?) do you feel you need better AF? (there are options) lower noise? (again there are options)
Between the 550D, 600D and 650D the changes are absolutely incremental. I changed from a 550D to a 600D because the flip out screen is brilliant for video, and the wireless flash is very useful. Haven't felt the need to upgrade any further. Thats said, I would say my new M (Figic5) is less noisy, to the point where iso 200 is like iso 100 on my digic 4 cameras, 800 like 400, and crucially, 6400 becomes to my fickle eye, usable with a little raw tweaking.
What would you want from a 750D that your 550D isn't doing, or the 600, 650 700 aren't doing?
I agree that canon need to stay competitive and that things have moved on maybe a little faster than canon has. However there have been quite a few new lenses, and not just expensive ones, maybe thats something to explore, expand your range with a macro or telezoom, or a fast tele prime like the 85 f1.8 or 100 f2.0? When Canon does come out with something new then you'll be even better equipped to use it!
The good news is that Canon often launches new tech on the rebels, which have usually been a bit ahead of the x0d series for megapixels and things like movie mode, perhaps as this is the most competitive segment, or where the most sales are, or where the range is quickest refreshed (or a mix of all of the above) but you'll usually see the newest sensors on the rebels.
I'm just intrigued as to why you want to upgrade? Is it an itch or a need?
All the best