What level of player should I play?
Any result between players with more than a 0.5 differential in rating is not taken into account if the higher rated player wins. This protects any negative ratings change for the higher rated player. If the lower rated player records the win US Squash will be alerted so that the result can be verified as this is expected to be a result in exceptional circumstances only.
In general, players should focus on competing with players who are within +/- 0.5 of their rating.