I'll offer the dissenting view:
I did the primary accelerated syllabus. At no time did I feel like I was at a disadvantage because of it. Only a few flights in contacts are cut out. In fact when I was going through the lousy T-34 maintenance situation combined with the sketchy weather, the program helped me get through contacts reasonably without having to do a bunch of warmups, since it was easier to get less X's. The other times you "accelerate" is some RI sims go away and maybe an RI flight or two. Frankly I couldn't stand to be in those sims so it was good to have less of them. PAs and Forms are unchanged since they are not as common to civilians.
Most will probably say "yeah you did less of those events but you got less practice!". True, but that was easily compensated for by my civvie time. Lots of people like to say that the military way is so different. While this is true, in my opinion there isn't much difference in PRIMARY. Sure, the IPs are tougher and have higher standards. The VFR pattern is noticeably different, and more emphasis is placed on EPs than civilian entry level training, but other than that, the substance of the training is not that much different in my opinion. Having prior experience MORE than made up for a couple of X's going away and I was happy to have more time away from building 89 in Corpus.
A lot of the guys I know with prior training (beyond a simple VFR ppl) did substantially better gradewise. That's not a guarantee, but it was a trend I observed. That goes for primary ONLY and after that all bets are off.
I digress. My point is: if you want to do the accelerated program don't be turned off to it immediately. It's only a FEW X's that get combined and the prior experience should definitely help you out.
All of the above is obviously first hand, but I've heard that echoed from other Commercial certificated pilots who have gone through, and ONE more point is this (if I remember correctly): As it was explained to me, the minute you are no longer performing well, they'll just stick you back on the regular syllabus.
The biggest thing is, the grades you get, divided by the total graded items. If you do well, then it's EASIER to get a much higher NSS because that ratio is easier to make a higher number, by dividing by a much lower total graded item number. If you don't do as well, then it can go lower a lot faster too, but they'll just stick you back on the regular syllabus and give you all the extra flights you'd have had taken out otherwise so you won't suffer.