Good question.
It's no longer really a question of whether or not you use the offsite, but whether or not you use the managers that are on the offsite to your advantage. A lot of people on the offsite, many of which have become good D.II and NBBA managers, will post their paths to success. You will no doubt have noticed a few of them on here already (Phyr, A-Dub, and the NT Manager). I would suggest that any manager who is in D.III or D.IV and in need of that extra boost sign up for the offsite. It helps you see a lot of information that the game may not present to you in any other fashion. For example, there are old crowd-sourced data that offers some indication of what shots are taken in what offense, and what positions tend to shoot the most in those offenses. You will also note a heavy amount of conversation about the u21 and NT strategies. In short, i believe any u21 manager, whether or not they have currently signed up for the offsite or not, will miss out on a significant tool at their disposal in job, and would probably do their country a disservice by refusing to use it as a tool.
I think if tough wins, i will happily aid him in the game planning against the opponent, something that he sometimes struggles with, because it's the right thing to do. Similarly, if I were to win i would think he would be willing to contribute to the scouting of the team because more than anything else he really desires to win and is really good at scouting. He's so good at scouting and getting people behind the cause that I tried to get him not to run so that he could keep doing that for us. I think without him here the last 3 seasons, you aren't looking at the same level of players as we have now, and as many as 5-6 managers will have not found additional info to aid in their own team's development.
Josh