Jelco vs Rega


I have an Avid Diva II TT with the Jelco ST 250 arm. Would changing the arm to a Rega RB 301 be a worthwhile upgrade or would it just be a lateral move or worst yet, be a downgrade. Thanks.
rsfphil
... Or upgrade to a Jelco 750. Owner feedback I've seen on these indicates they approach the performance of an SME 309.

If I ever re-arm my Technics SL1210, it'll be some version of a Jelco 750, probably the S-arm w/detachable headshell because I'm so used to that. The straight arm/fixed headshell version is pretty much what the AQ PT-9 was, right?
I put an Origin Illustrious arm on my Avid TT and the results were really great. Ortofon, P Windfield Cart is outstanding with this set up also.
Dear Rsfphil: The Jelco tonearm have to me an additional advantage due that it is a removable headshell design that permit ( changing different build/weight material hedashells. ) a better match between cartridge and the tonearm to have the " best " cartridge quality performance.

Regards and enjoy the music,
Raul.