I've been researching this. Still not clear to me. The old Fein hole was just round and blades slipped around, thus it was upgraded to the MM250. The new Fein hole is "8-point starburst." The Bosch PS-50 hole is "center hole and 12 small holes." The Dremel Multi-Max MM500 is "center hole and 9 small holes." The HF Multifunction Power Tool uses "center hole with 4 small holes."
Here's one answer I found on multiblades.com who makes aftermarket blades to fit both:
"Bosch and Dremel just introduced their own blades in the
American market and they come with a round hole that fit
on all Multimaster models."
OK, that's confusing, but it might work like this: the new fein multimasters (with starburst drive) are all downward compatible to their old round hole Fein style. So my guess is that by using the round hole compatible portion of the star drive, you can get off-brand round hole blades to fit. I bet they slip like the old round hole fein blades did. No way can the Fein make use of those auxiliary round holes for stability.
And at
www.toologics.com I found this:
"...you can purchase the Fein accessories separately and easily use them on your Bosch PS50...the Dremel Multi-Max...also will work with the Bosch PS50 accessories as well as the Fein Multimaster blades - BUT - you need to purchase the adapter separately."
Over at multiblades.com, you also find two more patterns...a 4-point starburst, and a wavey hole.
