In my view for what it's worth, I think hand knocking will beat a machine everytime. I haven't got a machine, but did consider one. However, I had reservations after speaking to a number of batmakers.
My concern is that not all bats are pressed the same and therefore a machine will not know how soft that bat is (and some I see are very very soft), which to me could cause issues. More so with others bats rather than mine, but why would you not offer the service for any brand of bat you a machine?
People are looking for a quick fix nowadays and knocking is seen as a huge chore, which it is. However, I'd always say knock in by hand and then do some throwdowns and a gentle net or two before going all out. If you say it's had 30 mins on a machine then people will just think it's good to go full pelt, which could result in more issues imo.
That said, i can see how it would help sell more bats.