So my handlebars were stolen from my Salsa Casseroll the other night, levers and all. (Argh.) The bike has a Tiagra 9 speed triple drivetrain, and Shimano discontinued Tiagra 9 speed hardware, leaving me with only Sora shifter to buy new. On ebay old tiagra 9 speed triple levers that aren't beaten up are hard to come by, but I'm seeing some 105 9-speed triple shifters that look reasonable. Are those compatible with my Tiagra parts? Will I notice any performance difference? Or should I just suck it up and get the Sora levers? (Guy at my LBS looked down his nose at their quality a bit, which has me leery.) Thanks for any help.
You can use either the Sora or 105 shifters (all the cable pulls will match). Sora 9 speed has the proper ergonomics (instead of the silly button that it used to use on 8 speed), so its a good shifter.
As for if you will notice any performance difference, both should shift fine (if the 105's are indeed in good condition) [if you're racing, maybe you'll notice a difference], but the ergonomics may be very slightly different between the tiagra-105-sora levers (but you'll get used to it) [it wouldn't surprise me if the current Sora levers are a slight modification of the 9 speed Tiagra levers due to trickle-down].
I'd probably suck it up and buy the Sora levers personally - brifters are too finicky/fragile in crashes for me to be comfortable buying used ones off eBay unless the price is very good.
My guess is the bike shop guy wants you to go 10 speed which will involve replacing a whole bunch of stuff, hence the upturned nose. Or general cyclist snobbery.