A few years ago a colleague and I did a comparative test of portable oxygen systems and demand regulators, at FL180. Interesting results (one mfg was less than chuffed
).
It was done in a turbo Saratoga, which climbed to FL180 at +1000fpm. I was impressed.
I keep half an eye on turbo options, and would buy a good TB21GT anytime, but have not yet met anybody whose engine made TBO, or anywhere near it. A friend seemed like he would be an exception but I have just heard he has had to change one pot, so I am back to zero examples... And the UK engine scene seems to have close to nil turbo / wastegate controller troubleshooting capability.
If I went to a TB21 it would need full TKS otherwise the higher climb rate would be of limited use (basically, one would do departures and arrivals in frontal weather / real icing conditions) and then one loses a lot of payload. It turns a TB20 (a great long distance load carrier, capable of FL200 @ ISA or FL170 at ISA+20) into a great long distance 2-seater, albeit improving the despatch rate from say 75% to say 95%. The TKS fluid is pricey too; I bought 20L for my prop TKS and it cost best part of £200. TKS is reportedly more effective than boots (for heavy or prolonged icing conditions) but one can see the attraction of boots.