The manual Fletcher machine is very high quality and good pro choice.
We have a really nice pneumatic unit in the shop. However, the dirt cheap little Inmes IM2 still gets a lot of use. But you have to know how to use it. Would be especially good for moulding that was flat.
Best feature is that if you're dealing with rather large frames you can easily slide the IM2 up to the edge of whatever table the moulding is on and starting pinning. Nice feature when you don't have as many tables as you would like.
There are some issues. That plastic, cylindrical "pad" is worse than useless and will damage most mouldings. We had to build several 3x3x1" oak squares covered on different corners with different thicknesses and arrangements of 1/4" felt to make it work with the 10 or so different mouldings we routinely use. That sounds kind of lame but in fact it's a great system and actually faster than the pneumatic one with even less setup. With the "squares" you can just march straight across the moulding finishing one full corner at a time. But again we don't use that many different mouldings.
Almost forgot to mention...we always glue first, let dry, then underpin. So for a framer doing as much volume as he could hope for, that's not so great. I really can't recommend using the IM2 for underpinning corners with wet glue. But for a 300/year shop, it's the bomb. Buy 4 clamps, you won't regret it.
One nice feature for newbies is that if you accidentally start to push up an existing nail, it's very easy to feel on the pedal and you can usually avoid that really annoying mistake most of the time.