oem shocks and some good springs are completey different to coilovers mate, if it's more comfort but still improved handling over oem you are after you are going about it the right way. You'll only really notice the difference in stability when you really push it hard, which of course should only be on track anyway, at all other times you will be glad you made the change.
I see lots of people choosing coilovers this past year or so and not being happy with the car afterwards, some going back to oem shocks and eibach springs or similar, and some losing the love altogether and selling up. When choosing coilies you really need to be prepared for what lies ahead and of course get the car set up correctly or you will be disappointed. I'm lucky with the 2 sets of coilovers I have had that eightspeed persisted with me and we got the car set up really well, but to further improve it we swapped the BC Racing for buddyclub N+, fitted lighter wheels, polybushes, roll centre adjusters, the right choice of tyre front and back and a 24mm arb and several geo tweaks. I didn't really know what lay ahead when I chose the coilover route, but followed it through anyway and now have a lovely end result, but to climb into my mates ctr with oem's+eibachs really shows up the difference in comfort levels...it's huge, but still a very capable road car.