One of the things I've found hard to get used to playing hardbat is the number of points I win on net balls. I don't keep track of these things but I feel like it's doubled or even tripled since my sponge days. It's a bit embarrassing really to be apologizing every fourth or fifth point and naturally people get frustrated after losing a dozen or two points per five set match from net balls. I also give up a fair number of points from topspin drives that tick the net and go long but the numbers here are smaller than the net balls that I win.
The other major frustration paradox with hardbat is the lack of barriers between adjacent table at most of the clubs I play at. The rate at which balls roll/fly/bounce into your court during the course of a match is perhaps one every minute or two. One of the attractions of hardbat is that because of the requirement that you mix defense in with offense you have the opportunity to play much longer points that in a sponge on sponge match. However the longer a rally goes the more likely it's going to be interrupted by a let call because of a foreign ball rolling across the stage. This limits the length of a rally in practice to maybe 10 or 20 strokes total with the longest, most dramatic rallies almost always ending in a let call. In order to offset this I've learned to not call a let ever when a ball rolls into my court because often if I don't call it my opponent won't either and the rally can go on a bit longer.
Rating-wise I'm stuck at the 1000 level for now. Overhitting and missing easy shots are the culprit. I also seem to have not really adjusted to the racket yet. Amazing after five months playing with it but I think it's true. On a basic level I still expect a sponge to be there with a lovely catapult and spin reversal effect to do some of the work for me. But no, the ball is met with nothing but wood and pimple and these simply shrug and look over their shoulders as if to say "Aren't you going to do anything with this ball?"