I would not want a rag or ragwing airplane which had been metalized, that generally makes them pretty heavy. The ragwing 170 has really puny ailerons- same size as the C120/140, on a longer wing. I owned one for 11 years ut never realized how puny the ailerons were until I flew it again after flying my C150TD for a couple months. The ragwing 170 might really benefit from VG's if they did a good job of livening up the ailerons.
From what I've read, all the strut-braced piston-engine Cessna's share the same airfoil, the NACA 2412, so that sholdn't make any difference between the 120/140 & the 150. A 1,000# early C150 with 100hp is under-powered compared to a 900 pound 140 with the same engine-- that's just plain old mathematics. When armchair-evaluating airplanes, I like to compare the power loading (weight/horsepower) and wing loading (wing area/weight) which together should give a pretty good idea of what to expect in terms of performance, esp if the airfoils are the same. The question is whether the advantages of factory-designed metal skin & the bigger flaps make up for it. Plus there is the "wow, that's different" aspect to factor in. There's lots of C120/140's out there, C150TD's not so much.