I have the stock brakes/pads that came on my caad9, the Tektro R520 dual pivot. They are kinda junky, but I don't know too much about calipers in general. I do know that upgrading the pads will be a big difference (kool stop is highly recomended?), but will buying new calipers+pads be worth it, if all I can swing right now budget wise would be Tiagras or equiv? ($50-$70 usd for the set of calipers range)?
I'm talking actual stopping performace/reliability, not weight.

I doubt changing calipers will be good money spent. Definitely do the pads and see where you are.

+1

tektro dual pivot brakes are actually very good. you will definitely not be getting any more performance out of tiagra brake calipers, trust me.

tektro brake pads on the other hand are notoriously awful. step it up to some koolstops or swissstops, both are very good.

also, the stock campagnolo record pads are amongst the best i've used. this would require you to buy carriers too, so probably not feasible for you.

I has the same brakes on my Trek 2.1 . Upgrading pads make a unbelievable difference. For such little money the brake are now awesome. Try upgrading pads before you think about replacing calipers.

I installed some kool stops on my mountain bike v brakes and stopping power and modulation improved dramatically. Inexpensive, easy upgrade.