I think it does depend on how disciplined you are. The beauty of TMR plans is that it's all done for you, you've got all your nutrition and the right amount of calories. When you do 3 and a meal, it's quite easy to just go over a bit on protein cause it would be a waste to cut off that 30g of chicken from the end of the breast, or to cut the brocolli in half cause you're now at 220g of veg - and what does it matter if you guess the weight of the protein and the veg, it'll all be fine...
If you approach your "meal" with the same amount of care and thought that has gone into the nutrition of the packs, and remember the vitamin too - then it'll be the same. If you're like me, you'll religiously measure out your water for the packs, but just chuck the veg in your steamer with a guess!