Curious what, in your opinion, made it the best move?
simple. the corvette is a much better all around sports car. in my c5 zo6, with just headers, a tune and some drag radials, i was just as fast as my 05 sti with a gt30 (before the gt35) and all the supporting mods (fmic, injectors, exhaust, utec em, etc). which car do you think is under more stress at those levels..the 5.7 v8 with 400 from the factory or the 2.5 H4 with 300 from the factory? running 11's was like going out for coffee in the vette..not so much in the subie. so for power and reliability, hands down, the vette wins. now for suspension and brakes. the c5 z06 was basically a factory race car, out of the box, it out handles my old sti. the sti needs a minimum of endlinks and sway bars to get it to handle since they understeer horribly without them. and the z06 was meant to stop from 170+...def had the edge over my subie's bembros. exterior wise.. thats up to preference as is the interior.
all in total, i spent over 12k in parts for my subie (turbo, fmic, ems, ppg dogbox to hold the power) just to run slightly faster than my z06 did with 1000 worth of headers and tires. bang for your buck..its no contest really.
hence why i sold my brand new 2015 sti for a c6 z51 2 months ago. i thought i'd give the subie world another shot, since i didnt like my gti, but once you drive a vette, you always come back.
