If you're a 5.0 then you can't play a 4.5 tourney. Most of the time (for 5.0 and up) they just have Open tourneys. Most 5.0's where I'm from don't play too many USTA type tournaments throughout the year. There are some Age Group tourneys and Invitationals that the upper level guys will play in but that's about it. A lot of teaching pros and former D-1 guys play 4.5 because they sandbag, not because there isn't competition at 5.0. Sorry if I'm a little cynical but it's kinda funny how bad it is sometimes (sandbagging). The sadder part is when guys get bumped to 5.0 and stop playing because they feel they can't win anymore.