Direct Drive

@dover The OL's use gimbal bearings. OL incorporates a floating bearing design  but I don't believe they're loose. My thought is that one would have to do a side by side comparison to determine which arms sounds better. I'd expect to see  comparisons of Rega and OL reviewed online but oddly I cannot find any. The Rega price tag is enticing.

Out of curiosity, are there certain stereo and/or mono cartridge that match up especially well with the Rega arms? 

I believe lighter cartridges are better for Rega tables.

@goofyfoot 

I use to sell a lot of Audio Technica OC9's which worked particularly well with the Rega arms.

The early Rega moving coils for me we're a bit "hard" sounding - partly I suspect because they had unusual impedance requirements and really sounded best with the Rega phono which used input transformers matched to the cartridge.

However I know someone who has run Shelters & Benz's with the Rega arms with good results and has just taken delivery of the top 2 Rega MC cartridges and is really impressed - they are way better than the older models and ahead of the Benz/Shelter's

Since VTA is not adjustable easily on the Rega arms going with the latest Rega MC's has a big advantage with ease of set up.

@dover Threaded VTA adjusters are available for any Rega mount. https://soundsupports.co.uk/Rega%20Related%20Products/

Of course Rega wants their customers to buy Rega cartridges but to me that seems limiting. I do believe in the compatibility factor, meaning certain cartridges perform better with certain tonearms. But Clearaudio cartridges with Clearaudio tables and Rega cartridges with Rega tables; on that I'm not yet sold.

I’ve used a van den Hul MC one Special with excellent results for about 10 years. Great stylus life and detailed dynamic SQ.