If you decide to go for sti, I have an almost new pair of 2016 tiagra 3 x 10 levers spare. Took them off Olive after 50 miles, and put on old 8/9 speed bar cons, running in friction mode, operating campag veloce fr & r mechs, with 10 sp shimano rear cassette. If you change to bar cons, just leave your brake levers on, with all the gubbins in side and pull out the gear cable. Ran mine like that for 5+ years on another bike.A 10 sp cassette will IIRC fit on your 9 sp free hun body.Spa / stronglight for the chainsets and bb me thinks. Or..do what folks used to do, before the throw away society, just buy new rings. Re brakes etc, if it all works well enough,( you are still using it aren't you) then leave well alone,it'll turn into a full rebuild otherwise. Re bar cons, if you run bar cons in friction, your 'worn out' rear mech will work fine, as you quickly get used to trimming, and you can then run any rear mech, with any (campy or shim) rear wheel, 8/9/10/11 sp. I would NEVER go back to sti, even my full sus mtb runs 8 sp thumbshifters in friction mode. OR.... Run bar con for rear mech, on lhs of bars, and downtube shifter for front, on lhs, then put an insert bar end mirror on the rhs, after all, you do all the gear changing with your left hand when you drive.