Thank you both for your feedback, that is helpful. So it sounds like I'll be OK using a 9 speed cassette. It needs a good cleaning that's for sure!
If everything works ok then I would leave it as 8 speed, doesn’t make a great deal of difference in my opinion. You could replace with 9 speed when your current set up requires replacement through wear and tear, until then don’t waste your money.Thank you both for your feedback, that is helpful. So it sounds like I'll be OK using a 9 speed cassette. It needs a good cleaning that's for sure!