I started with 600D at the end of last year and have just picked up a used 7D.
The 600D was my first DSLR - arrived the day before I went for a weekend away - first time I turned it on I looked and realised I didn't have a clue! Had read plenty of theory but not got any practical experience. So for that weekend I stuck it on "P" and just snapped away.
Since then I have spent huge amounts of time a) shooting using manual settings in lots of different situations and b) ridiculously huge amounts of time on here and other websites, and also subscribed to a couple of photography mags. So I have learnt a lot in quite a short time before deciding to get the 7D - and to be honest I only got it when I did as I saw a great deal for used one otherwise I would just have waited.
Have only had one chance to take 7D out since it arrived, and although through it still being so new to me I probably missed some shots I would have got with the 600D, I did not feel overwhelmed - and came home with enough keepers (perfectly sharp!) to be happy.
None of which answers your question - at the end of the day you probably have a pretty good idea what your heart wants, whatever anybody else's advice is. I am sure you will have a great time whatever you decide - but remember this is meant to be fun, it is very easy to get obsessive with gear (and I hold my hands up that I have been through that) and forget that the whole process is meant to be enjoyable!


