Please don't expect me to make a habit of it!
What I forgot to add is that if you are going to buy a plane that is totally shagged and you want to run it into the ground or on a very tight budget (which is basically what happens in a large % of the GA scene, especially the training fleet) then retractable gear is a bad idea. People have all sorts of problems with it, made worse by the unwillingness of maintenance companies to do what they see as "extra work" for their standard Annual charge of say £2500 or whatever.
I recall flying some in the States with 50lbs of lead shot in the luggage compartment behind the seats. Without, it would have been very close to, if not exceeding forward CG limits with 2 people up front.
Which is not very useful
I recall reading a similar story about a Bonanza, I think. In comparison, the TB20 is practically impossible to load outside the envelope without exceeding the MTOW.
It's the Turbo that I question. I've only found an advantage when operating above the altitude at which a normally aspirated engine needs full throttle to maintain a desired % power.
Yes; it depends on your mission profile. In Europe, a turbo means an IR, practically. And oxygen, of course. A TB20 will reach FL180 in about 30 minutes and will make
FL200 "some time" after that
I would expect a turbo arrow to beat the 30 minutes by a decent margin; the Q is what value this brings in practice. I think that to get that (the ability to climb through icing layers) one also needs de-ice. If I bought a TB21 I would get one with full TKS.