After using a pull-behind sweeper for a few years I upgraded to the JD MCS this summer and have been thrilled with its performance.  I have primarily conifers (white pine) in my yard with a few deciduous species.  The bagger does a great job and picks it all up.  Like others have said, even though its three bags it can fill up quickly.  I went over some fairly deep areas I thought for certain would take multiple passes and cleaned them up on just one pass.  I love that I don't lose the convenience of the HST by not being limited in backing up when mowing like you might find with a different system.  I've read others complaints about the MCS and haven't found them true.  I might just mow more frequently, or slowly, but haven't had any problems with clogging.  It was pricer than I would have liked, but in my opinion it has been well worth the investment.
Has anyone found a front-mounted thatcher so I can combine everything in one pass?  I see JD makes one for the x series, but a local dealer couldn't find anything for the 2210.