I've always been afraid that my MRs would turn out like that, but fortunately I've had rather positive experiences doing mine.

I did a similar MR earlier this year on US Airways to lock in Platinum status on a challenge (DFW-CLT-PBI-CLT-LAS-SFO-PHL-FLL-CLT-SFO-CLT-PBI-CLT-DFW, four transcon segments and two redeyes in four days, with a conference in the middle). I got upgraded on all of the segments except the two redeyes and was able to VDB for a voucher and skip two segments while still getting original mileage.

I did a series of LAX-BOS runs to go from 0 to EXP on AA last month, and everything went perfectly. I had one delayed flight which didn't affect anything and was able to VDB for a $500 voucher on another flight without impacting any other flights. I was in coach on all but one of the transcons, but always in great seats (exit rows, bulkheads, flight crew rest seats, middle three to myself a couple times, etc.)

I would agree with those suggesting longer single-city RTs for MRs. It's far simpler, and if you can do transcons or international, it's about the same price and compressed into much less time, with very little stress. Especially now that I'll have EVIPs and EXP status on AA, I'll probably do some international MRs next year to maintain status.