While I have been a professional pilot for a little over 10 years; I have only been a plane owner for a year now (take my opinion with a grain of salt), and my first plane was an M20J so I may be a little biased. I did look at getting a M20C (and flew one), along with a C182 and some pipers. There are a lot of opinions here that I could quote and agree with and a few people have said it already, but if you have the resources why not. That said, how much of a gain are you getting, the listing didn't say anything about speed mods so I would assume it doesn't have much. 6k+ hours on airframe might increase your insurance a bit, but overall looks like a nice plane. If the means are there you can find a J for a couple bucks more if you are willing to search for it. The other day I did some formation flying with a hangar neighbor with a C model, he was running 24/2400 and I was 21/2400. My point is if you have the resources and find an older J that isnt too much more, I think you would see a bigger difference. The guy with the C has also flown back seat in my J and raves about the extra space in the long bodies, so if you plan to carry more than 2 people that might be a consideration. Some people were saying don't run the numbers for a J/K, but I feel price wise the jump from a nice C to a decent J isn't as much as a J to a K and obviously a C to a K. I went with the J over the C because it was my first plane and everyone I talked to said I would be wanting a long body after awhile and I found a nice J that wasnt much more than the C I was looking at. Now if I already owned a plane I think that would be a different story, or maybe not. Again new plane owner so a lot of this is new to me.