I'm on MRC, have been since May and I love it! I've lost 44lbs over summer break (i'm a teacher). I could rave about the program, but like several others, I'd recommend searching the forums for MRC...there is a group of us there and we'd love to see you.
Some of the high nutrient drinks have aspertame, others don't. I choose to take the ones that do not. They have splenda instead.
I was VERY skeptical of MRC before I joined, but after watching 2 close friends lost over 75lbs in under a year and watching my brother lose 80lbs in 6months I was convinced and I talked hubby into joining. I am rarely hungry and have lost an average of 3lbs a week (just lost 10lbs on vacation)
Every diet has its plusses and minuses...this one is expensive...But like someone else mentioned...that is a HUGE motivator for me. I take the bare minimum of their products and I have had great results.
This plan is best if you have alot of weight to lose. I started at 353 and want to lose 200lbs. I don't know if I'll actually go that far, but I'm very sure that I can with MRC.
Good luck losing on whatever plan you chose. (Feel free to IM me if you have more specific questions.)