What's the difference between the Kipon/IBE and MTF B4 to S35 optical correctors?

[Geffen Avraham]

IB/E Optics makes a popular HDx35 optical corrector, but at a very high price. Kipon makes a slightly cheaper one, but likely with the same optical formulas. Both are rather large.

https://kipon.com/product/b4pl-s35/

Meanwhile, MTF Services offers one for half the price and size. Relatively little is listed about it, but the "catch" may be that it requires a B4 with an internal 2x doubler to work on S35.

This could be a plus for me though - perhaps I could turn it off and use it on S16 as well.

Has anyone used this adapter?

https://mtfservices.com/products/b4-2-3-to-arri-pl-adaptor

[Steven Jackson]

 I can find very little info about these adapters and whether they correct chromatic and spherical aberration.  I'm in the market for one for super16, which I see they offer, but just almost no info available.