First off, MeanCityCycles is one of the best companies I've ever dealt with. Everyone I spoke to was awesome and more than willing to answer all the questions I had. Scheduling was a breeze and the turnaround was super quick. Plus, they go out of their way to sell you what you need, not what is the most expensive!
I had my seat done over the Winter and when I finally got back out this Spring, I felt an immediate improvement. After an hour on the stock seat, I had to take a break and walk around for a bit. After the double decker foam mod, I feel like I could ride all day without problems (Spent 5 hours on a trip over the weekend and felt fine once I got back home). I also had the passenger seat done at the same time and besides not shifting around as much while we ride, my wife has said she is much more comfortable as well.