As someone who went on kind of a wild goose chase to find a better phone than 595s, I can say that the 650s are definitely worth the upgrade. I knew I wanted a headphone with more bass and so I tried the DT990s. They had a much bigger, airy soundstage, which I liked, but the mids were definitely inferior to the 595s. So then I tried the Denon D2000s, which were more fun than the 595s, but I found them a lot more fatiguing. So I finally settled on the 650s, which I worried would be boring out of my Hornet (according to numerous posts). They were exactly what I was looking for. Bigger soundstage, more bass, more refined, but in my opinion they're still fun.
What surprised me was that I preferred the 595s to both DT990s and D2000s. They are good headphones. But the 650s are definitely better, to my ears. My one recommendation, though, is that you try to find them used, as it's not uncommon to see them on the FS forums in mint condition for around $260.
I can't comment on the recable. They sound fine to me stock.