XP-G on reflector made for MC-E question

[videoman]

I would like to use the Khatod square reflector KCLP 1278CR that is made for the MC-E with a XP-G led. It is a 65 degree square spread type. I would be using it on a 20mm star. If the led placement is not exactly (give or take a few mm) as the MC-E, will it have a drastic change of spread, focus, artifacts etc.? I can accept a slight decrease or increase of spread angle. What other considerations/problems might there be ?