Yes, there is a difference, but it is very slight. IMO, the OL is slightly better, due to the method of coupling the end-stub. But, it is really splitting hairs, and it is much harder to install the OL end-stub, and it is better to send the arm in to have it done. The Expressimo is more easily done at home. So if you want to DIY, then maybe the Expressimo is a better choice. If you are after the last 1% of sound improvement from the mod, then send your arm in to OL for the installation of their mod. While you are at it, it would be a real good idea to improve the wiring, which is a known weak point in Rega arms. Also, the Expressimo Heavyweight Counterweight is a very worthwhile addition to consider with your new structural modification. And if you don't have a VTA adjusting collar, that is mandatory for a Rega arm. Both OL and Expressimo sell those.