Rega RB-250 a major upgrade?

I currently have a Thorens TD-145, nicely modded. It's time to change the arm as the hum due to the old wiring in that arm has finally driven me crazy enough. Plus, the blue wire is about to disappear into the arm after breaking for the third time. I don't want to rewire, major pain, and it would cost a lot to have it rewired. So, since I can't afford an SME, and really can't spend even $4-500 for an arm right now, I'm looking at a Rega RB250 for about half that. Would this be a major upgrade from stock, or should I spend the $150-$175 I was quoted to rewire stock?

The decision what you will do is your own. I know that the rewire kit from Incognito (for example), which was offered for some time, was a worthwhile investment and all owners said: "Great".
I have listened to the RB-250 think it would be a good improvement on your TT. Plus there are great mods for the arm that can raise the performance higher when youre ready.
I imagine you mean the rewire kit for the stock arm?
If so, perhaps I can recommend the specialty shop I sent it to use that (or similar) for the rewire-

But I think for now, I'm gonna stick with the stock arm and quality rewire. I like the auto shutoff feature, I'm lazy (and forgetful)!