I'd say that if you're planning to stick with the stock cam and you've got other intake and exhaust mods already, go ahead and grab the 1.7rr's along with a better set of springs. But it’s going to do little for a stock engine, so make it one of your last mods.
I've got them on mine (1.7's), but i've also got ported heads, intake, full exhaust, pulleys, CAI, gears, etc, etc. Don't expect huge power gains either way, but they're worth a few ponies along with other mods. Probably in the 5-10fwhp range.
If you're planning on swapping out the cam, the stick with the 1.6rr’s and concentrate on cam selection to provide any added lift you might want. 1.7rr's have been shown to place added stress on valve train (increased side load and friction on valve guides and valve stems), especially when the horsepower and RPM potential starts to climb.
How's that....clear as mud?