I LOVE Alder...built an entire kitchen with the stuff back in the 80's...oops, I meant the late 70's. (Well, I also used some Birch Ply with that build, too.)
It does machine well on a CNC, as well. Trying to remember which POM I used it on...was it a CarveWright or Vectric POM? ...can't remember. I'll look for some Alder blocks for the rotary...I also found some Poplar blocks at the place I bought the Basswood, so I'll try some of that too. I've not tried Poplar on rotary, so maybe I'll get lucky this time.