Anyone move from 5d to 50d or 50d to 5d

I've read and read and read all the hi iso comparisons between the 50 and 5d and it looks pretty damn close. What I'd like to know is if anyone bought either and switched. I'm doing a wedding and I see that the 5d is phenomenal in the low light arena but I see that the 50d can hold its own as well.

not sure if this is relevent to you, but i have a 5d and a 40d, which judging by reviews theres not a lot of noise difference in the 40/50d ( time for several million insulted 50d owner replies ). but purely judging by the 5d vs 40d the results are worlds apart in the 5ds favour. now i usually print at a1, so printing small at a3 or so the difference wouldn't be as noticeable