Hi Andy
OK - it all depends on what you are going to use it for. I have a Ryobi table saw and it's OK-ish. I will replace it at some time or other.
With this table saw I always struggled with large sheets (or even medium size sheets!) of stuff like MDF and plywood. Then I bought the TS55 and guide rails and IMHO you can't beat the combination. Ideally you need an area on the floor about 8 x 6 feet, stick down a sheet of fibre board, stick your MDF or whatever on top, set the TS55 plunge depth to just cut through your material and away you go. I also bought the 90degree attachment to go with the guide rail. So easy-peasy.
I wouldn't use the TS55 for cutting down stock to make table legs though or similar size work. The Table Saw is much better for that. But anything wide (like floorboards or kitchen workstops for example) the TS55 winds hands down.
I know that Tim would go for a 75 if he had the choice all over agin....guess he'll be along soon to confirm if that is still the case!
All IMHO. You might want to sound out John Elliott who had a table saw, then sold it when he got his TS55 but is now getting another table saw.