I'm am trying to decide whether to get the Silent Partner Pro ball machine or the Tennis Tutor Plus Player. The Silent Partner can shoot balls out at 95 mph, while the Tennis Tutor only does 85mph. Is the difference that evident and a major thing to consider? I'm around a 4.5 player wanting to get better. Weight isn't an issue, but reliability is. I've heard that both are well built. So if you were going to buy one, which one would you choose? Also, I'm not sure but do ball machines require any special balls? I was going to buy the Wilson US Open XDuty Tennis Balls, but I wasn't sure if they would work on the ball machines. Thank you so much for your help!