Picked up a Makita compact die grinder and I'm still a big fan of air grinders but figured I'd share my experience with it so far.
The Makita got hot the first time that I used it(over an hour straight) but didn't so much after that I noticed.I have used a Dremel and a 1/4 die grinder for porting work which was workable. The die grinder was mostly used with little sanding drums. The heavy work was with the air die grinder. My problem was with the Dremel and that was it would get very HOT in a short amount of time. I would have to let the Dremel rest and cool down so I relegated it to finish and mild metal cutting but mostly the little sanding drums and cone shaped abrasive rolls.
The very first thing that I dabbled with long ago, was cleaning up some spark plug threads on the chambers in those heads in the video with my dads old Dremel. It died before I got em all done and I just bolted them on since the heads ran fine on the two previous engines LOL To be fair it had gotten kinda wet previously from some light flooding.I never had much luck with a Dremel tool doing most anything. They seem to break when I use them............
I ground a bolt head off the transmission crossmember on the Tbird with a little Dremel because the angle grinder wouldn't fit. It did take me 4 very uncomfortable hours though.Come-on guys the Dremel is made for playing with model planes, trains and automobiles not for machining the real things.
Stay tuned, got a suggestion that I'm gonna try here soon. Those burrs look like a good deal but I use mostly oval/egg and I buy mine from Buckeye Carbide's ebay store or Mcmaster carr mostly . Also I buy my sanding rolls from mcmaster carr or some bulk from Zoro with a discount code.Have the makita too- its a monster! You gotta be paying attention. I do also have the same speed reduction thing - tried it on lathe but only got about 10% reduction, I have found the alu bits to gall up under such crazy speed! Wish it was a little variable..
I found some EXCELLENT bits on amazon, man they kick ***!! https://www.amazon.com/gp/product/B07FM1BL5T/
And alot of harbor freight sand rolls - man the makita just rips em up..