What did you find was the biggest leap for you? (I know the leap in a body purchase may not coincide with big leaps in technique and artistic vision though ...)
For me it was AE1 > A1 > EOS 620 > EOS 3 > EOS 1v HS > 10D > 1D Mk II > 1Ds Mk II > 5D > 1D Mk III > 5D2 > RS?
AE1 taught me the fundamentals
A1 allowed me to capture more due to better/more useful metering
620 was a setback as the AF sucked, but the technical back was fun
EOS 3 eye control did not work well for me, I should have just got the 1V
1V HS was great way to waste film, but I got very good at reloading
10D was the biggest leap for me, with the instant feedback of chimping
1D Mk II increased my keepers
1Ds Mk II was a great increase in printable images
5D was a great landscape body for me
1D Mk III was the biggest setback due to AF failures, I should have dumped it, it sits on a shelf with 6x7 gear
5D2 is a great body and was my last after the career impact of the 1D Mk III
RS will be my first new gear in over a decade, and now that I am retired I can focus on landscapes again