Seems to me some of the posters above have no clue, never owned a Rega.
Facts are -
All Rega arms are 222mm pivot to spindle, 14.5mm overhang
Rega arms are designed for Stevenson alignment.
Rega protractor supplied delivers correct overhang and aligned for Stevenson for any cartridge, Rega or otherwise.
If you want to use Baerwald any 2 point protractor can be used - I use a Garrott 2 point protractor for most installs.
Experiences ( hands on, not from AI, and not speculation - P9/P10 )
Stevenson alignment works better than Baerwald on the Rega arms.
Non Rega cartridges - I have heard various Benz, Lyra Delos, and most of the Rega carts. The latest Aphelion 2 is a superb cartridge, a big step up from previous models. The Lyra Delos is superb for the price.
Most folk who buy Regas understand that you need to buy spacers to use non Rega cartridges for VTA adjustment. Rega dealers sell them.
The only thing I would suggest is that your antiskate is too high. Generally according to studies by Shure and others, antiskate should be about 25-30% of tracking force. Have a look at your cantilever from front on when you lower the stylus - you can usually see if it is pulling one way or other. I generally start with antiskate at 1/3 of tracking force and then check the cantilever, and listen to very small changes either way.