"Skill" level between entry level and top tier players of an NTRP range differ drastically. Also, many people are "type casted" into these roles because people (on this forum especially) seem to have each NTRP level laid out in their minds.
I have seen 4.0's with 100+ mph serves, but I have also seen 4.5's with solid 80 mph serves, with high spin. I have seen 3.0's with 70 mph forehands, but no backhands, or volleys. I have seen solid 4.5 "Continental" all around players that will almost never make an error. I have seen 4.5 players who played college a few years back...
Really, NTRP is just a rating system and does not define the player at all. The best thing about playing up a level is that you're challenging yourself to get better. You also have to realize that at some point you will plateau and you will be low to mid range (because thats NTRP's design) and you will have to accept that level, or sandbag down.
Most players will try to move down. Great players will try to move up. Dont sell yourself short, or rely on NTRP to define you.