Only thing missing in any of the Mellotron romplers is the liquid real time audio rendering of the original mess. Don't know how significant this is regarding the endpoint sound, but must weigh in the hardware limitations/ contributions as we regress from the prototype.
The original hardware was a wash of imperfections. Wow, flutter and whatever else could fail in the mechanical nightmare.
We can't recreate this chaos with sterile digital samples.
Cudos for the Tool guys for offering their interpretation for sale. In my estimation, overpriced, remote from the original mark.
Can get many free mellotrons if you need a sterile sampler Synth Edit origin. As was advised by Cecilius, if you want a good mellotron commercial plug, go for M-Tron Pro. Tools is cool, but spend the cash elsewhere with better representation and versatility, given their asking price.
John