EF Lenses on R Mount (f/1.2 portrait primes)

saltydogstudios wrote:

I've been interested in getting into the R Mount for a while now with the 50mm f/1.2 and 85mm f/1.2 lenses for portrait work - both natural light and studio.

Adding all of the above to my cart ends up being around $8000 USD for the body and both lenses.

But the latest DP Review video has me thinking - why not get the EF mount equivalents?

Sure the lenses are older and the autofocus and optical performance may not be as good - but with some used EF lenses, my cart is now half the price (body, two lenses and adapter).

Does anyone who has experience with both the EF and R versions of these lenses have an opinion on this?

With the lenses at less than half the price of the R mount versions, it seems like a no brainer - I can get started and then trade up to the R versions if/when it makes sense.

Is there any major reason I would regret getting the EF lenses?

I used Canon 5D series for many years and had the 35mm 50mm and 85mm L lenses.  When I switched to Sony I sold the 5Diii bodies, but kept those lenses. I call it nostalgia, my wife calls it hoarding. 
I recently bought a Canon RP just as an excuse to get those lenses out of the cabinet again. Of course they are still as capable as ever, but their character and rendering doesn’t have the state of the art precision of, say, lenses like the Canon RF 50/1.2 or the Sony GM 85/1.4 (Neither of which I own). 
I sometimes want images with feeling over precision, so those last-generation lenses are perfect for those occasions. For example, I’d describe the EF 50/1.2 as having more of a “glow” when used wide open, than the impressive RF version which is incredibly crisp.
You seem to be making a decision based on the cost of EF vs RF lenses. I see you are someone who cares about the flesh-tone differences between camera sensors as you have spent time on creating an interesting colour comparison shootout chart. So my suggestion would be that you research the considerable differences in the rendering between the EF and RF lenses and make your purchase decision based on what style works best for you. 
Saving money is pointless if you’re frustrated with the results.