I can't say from an AROTC point regarding going to a bigger school to get a better military career job, but for the AFROTC this is not necessarily true. The reason why is that the dets at bigger schools can be more competitive from within the det.
For example, ERAU boasts that they give the 2nd most amount of UPT slots, only after the AFA. However, what they fail to mention is that their statistical % is lower than many smaller dets. For example VT gives less UPT slots, but % wise the cadets chances are much higher. I believe, and please don't quote me, but ERAU gives about 50% UPT slots to their cadets, whereas, 85% of VT students get UPT if they request it.
Just because it is bigger, does not necessarily mean it is better. Again, this is for AFROTC, so AROTC could be bigger does mean better chances. I would suggest that he talks to the BN commander and ask PERCENTAGES, not the number, but PERCENTAGES if he transferred to A & M.
Additionally, in the AFROTC world, the commander has an input, because they write a rec to the board regarding the cadet. If he transfers as an incoming jr., the command will have very little personal background to write the review. On top of that his current command would know he is leaving, thus they would most likely not offer him a BN position as a sophomore cadet, because they will want to give it to a cadet that is staying. Finally, as they rise up the ranks the fall positions are given out in the previous spring, which means for his fall semester he most likely not have a position within the BN. Now what does that really mean? It means that as his peers/yr group move up the ranks, they will have held positions, while he is behind the 8 ball with probably 2 semesters of no positions. The career board will see this, and if they have a choice to give the last slot to either your DS or the cadet that held jobs during those 2 semesters, and both have the same gpa, which one do you think they will choose?
I would suggest that he contact A & M asap, start the process now, so he will have 3 yrs at one BN.
Now throw that all in the circular filing cabinet, because it is only MHPO.