I'm a bit late to the party, but I did the Mongol Rally in 2009 and it was fantastic...and went to the launch in 2011 and in 2012.
WhiteRover - I know Tommy and Will as well and actually helped them with more than a few things for their trip...and yeah..they loved it so much they did it again this year
I was headed to Africa last year, and was containerizing my vehicles, so was actually able to take over a bunch of bags for the two of them since they did RORO.
DetSlider - I'm in Richmond, so if you ever want to chat or meet up, let me know. I love talking about all things rallying!
I met people doing the Mongolia Charity Rally and I was part of the Mongol Rally. There are a few differences, but they both have changed and are continuing to change. The ony big complaint from the Mongol Rally folks was cost. The one big complaint from the MCR folks was that there seemed to be more parties and more comraderie amongst the MR people. The MR though is slashing their fee by 50% for 2014 I believe and wiping out the vehicle restrictions (if you are brining you vehicle home).
As far as the charity stuff, they are really both the same. You raise money for charity...whether you raise $1k or 50K, it all went directly to the charity and not through the rally organizations. The difference was the fee. At least in 2009, the MCR people seemed to not know as much about what was going on and were more on their own. That's not a bad thing, but just a difference. The MR offered a launch with fanfare and a party...a party in a castle...and a few finish line parties along with (a bit) of guidance along the way. By this I mean you would get an email that would say "Recent reports from Team : XXXXXX - border to Kazakhstan at Semey is closed for 2 weeks." stuff like that.
Regardless. The countries are great...the people are great...the road conditions are pretty good...and the areas are pretty safe. A great first rally experience. Plus, there is a nice safety net of there always being some teams in front of you somewhere...and always some behind you somewhere!