You're going to use this on a minimill? Which minimill is that?
Are we talking 150 Lb Chinese minimill or 850 Lb? It makes a difference.

FWIW, I bought one of these (R8 TP insert holder) for my old Bridgeport 1J
head machine. The machine wouldn't take it. I guess its for sale if someone
wants one.

On my Excello (WAY more rigid) I find the high performance inserts are
worth the extra bucks. You wouldn't believe how fast you can remove metal
with a Sandvick R-390 insert. Same deal with my 10EE, the CNMG inserts with
the LF chipbreaker remove way more metal and give more accurate results. By
that, I mean the TPG seems to cause more deflection pressure and gives not
as repeatable results. Of course, both these inserts are 5X more expensive.
You gets what you pays for.

Karl