Rega Planar 3 RB880 Upgrade Worth It?

Yes.

I know most of you will say upgrade to the 6 or 8

I would say upgrade the TT - and I have heard a Rega P5 with full groove tracer mods.

However, if you want to upgrade the arm as an interim measure, yes the RB880 should make an improvement in precision, timing, etc.

Alternatively have a look at the Audiomods 6 - for similar money its an outstanding arm with VTA on the fly and more saleable as a separate item should you upgrade the TT later. I put one on my Platine Verdier when I sold it and the performance was way above the price point suggested - very good. You can order a Rega fit for the Audiomods - in other words a straight drop in replacement.

Yes upgrade to a Planar 8 or even a 10 if your budget permits it. You can only get so much performance from a P3 regardless of the mods. Another issue is resale you won’t get much(if any?) money back from all your time and investment. I have a Rega P9/RB1000/Spiral Groove feet/HRS weight/Herbie’s mat on a Sound Mechanics platform and have considered a "so called" upgrade with a VPI Classic 3 or Clearaudio Ovation neither deck was an upgrade but a sideways move. I will be ready for my next cartridge upgrade this fall.

@dayglow ​​@dover thanks for the responses!  Understand the RB880 would be an incremental step up...but if I did that, is the P8 really that much of an improvement with the same cartridge?  To your point, I'm likely not going to get anywhere near the amount of money back that I've invested in my P3...so if I'm going to shell out the money for the P8 I would want a significant audible improvement.  

@dj_xwing  With the Planar 8 your getting a new skeletal plinth and glass platter that will be an improvement over your modded P3. Your the only one that can answer is it worth the cost. The positive is your getting a new very reliable table that will hold its resale value for many years. If you keep your P3 to long you will have to deal with DIY "Dumpster Divers" offering next to nothing if you want to sell.