I don't have any of the stuff you mentioned, but I do have lots of suspension stuff. Quality shocks/struts do make a difference. Springs rates will affect performance way more than the amount of drop. Sportlines are probably a good bit stiffer than stock, so with a good set of shocks/struts, your car will handle much better than stock.
I've got H&R Race springs which are pretty stiff, but with Bilsteins, they are not too harsh at all. In fact, highway trips are absolutely comfortable and corner carving is much more fun and more safe. I'd recommend new endlinks with eurethane, too, if yours are stock.
Subframe connectors are cheap (less than $100) and will stiffen the chasis. Very noticeable and it will prevent many future squeaks and chasis wear-and-tear. Corner carving is much better with subs.