I have a 30". I have had no problems with it....I have a friend at another shop with a24". She hates it. I think there is a big difference in the way the operate from a 24" to a 30" besides just being different sizes....
Having owned both a 24" and a 30" Panther I can state with some authority that they are identical in operation.
A Panther is probably the best of the el cheapo plotters. With the two I owned I had to replace the tool carriage once in the 24" and twice in the 30" in less than a year. As plotters go they're sort of heavy handed and without a lot of finesse and elegance. The manual is from hell. The stand and media roller mounting fasteners are cast pot metal Allen heads and one brisk turn with an Allen wrench and they are well and truly stripped.
If you've never owned a high end plotter you'll think the Panther is just fine. I did until I bought a Graphtec. The differences can sometimes be subtle but are telling and add up to night and day. Now you couldn't give me a Panther.