To be honest, unless your an absolute stud, there really is no point in singling out what division you want to run in.
d1 has its powerhouse teams, just like in every division, and those are the teams everyone wants to run for. So, if you're good enough to run for colorado, stanford, wisconsin, ark.. etc... than by all means, go for it.
Where I get frustrated is the guys who go div 1 to an average d1 school and talk like their the real deal when it comes to racing d3.
I've seen plenty of great d3 teams mop up on average d1 teams, just as i've seen great individuals d3 mop up on better d1 guys.
Its not to say that we're underated, its just to say that the further you get from that top 25 d1 teams, the less and less divisions have to do with your improvement.
Example, a guy who runs for say, UW-Milwaukee, can say he runs d1, but the reality is, there are probably 3 WIAC teams any given year that are more than capable of beating them.
So, to answer your question, if you were shooting for top 35 in d1, then you probably belong there, even if you ended up 50th. But I think for guys who are finishing 35th in the region, then d1 isn't a neccesity, just a preference of school or program.
Plus, d3 gives guys that wouldn't have a shot in hell of ever making nationals d1 a chance to contribute and a chance to shine. Its less talented pool overall, but its just as competitive when put into perspective.
I think d3 rules.