Regarding choosing 900 vs 200:

You have to consider upgrade time as well. 6+ months of reserve (versus 2-3) means you've lost up to 150-200 hrs of block.. So you're hitting 1000 hrs of 121 3-6 months later than you would've been on the 200.

...And then when you do upgrade you have the choice of maybe getting a line on the -200 or sitting reserve forever on the -9.