400 having to throttle back to avoid overspeeding, and the 146 driver caning it for all its worth.
Well you must be 400 pilot then.
The 146 might be slow for a jet, but it is quicker than the Q400, and yes, we too have to "throttle back" to avoid overspeeding. How do know this? I have passed many a Q400 in a 146.
It is demotion from the point of view that, if you ever want to move on, the fact that you have gone from a jet to a turboprop will limit your opportunities. You might say that the Q400 is more advanced etc, but in reality turboprop time is never as valuable as jet time - if you don't believe me, ask around amongst chief pilots in larger (all jet) operations. Many see the 146 (as the slowest jet out there) as being the minimum qualification. The Q400 is smaller, lighter, and simpler, and none of those qualities make it a good career move. And, as you point out, virtually impossible to land gently.
And, quite frankly, I would much rather be in the relatively quiet environment of a 146 cockpit than in the somewhat noisier Q400 one. I would far rather have the antiquated 146 systems than the temperamental Q400 computers. And I have no desire to have to go back to iced-up props, inop prop synch systems, and all the other crap you have to put up with when flying turboprops. I like having an APU too.
People will go from the 146 to the Q400 because they are forced into it, or because they are offered a carrot - no other reason.