Ground Control are definitely the safest way to go, if one must have coilovers, so to speak. The only issue will be getting springs of the proper rate and length. can be hard to find springs with rates anywhere near oem, or even regular drop spring rates, which are usually somewhere between 2-3 kg (front) and 4-5 kg (rear). The biggest plus is that you end up using oem designed struts, which are at least valved accordingly for our car, and will generally handle slightly higher spring rates without issues. The Tokico Illuminas and Koni Sports are probably the safest to use for this purpose, though the Illuminas are now harder and costlier to obtain since their reorganization. Konis probably also will handle higher spring rates a bit better than the Illuminas, at least from most peoples testing.
Another concern though is the total spring drop. Both of those struts will handle about an 1" or so of drop without too much problem, but going much past that and you're going past their design limits and will cause premature failure. You can always look around for specialized short stroke struts from Koni, but you'll also have to make sure their valving matches the spring rates, and car weight (a bit of work, lol). Usually after installation of Ground Controls most people end up with something not that much different than a set of regular drop springs and struts, as they will set the ride height once, and never touch it again afterwards, as it's just too much of a hassle. despite how cool coilovers sound I'd personally tend to recommend a set of Eibachs and Konis, and leave it at that. The Eibachs are a proven spring, give about a one inch drop, and have decent fast road/autox spring rates. The Konis are also well proven and offer a lot of adjustability that is easy to set.
As for Ceika, yes, they appear to make customized coilovers. Like some others they have a huge application list, and probably have the majority of their parts built by a manufacturer that supplies a handful of other general coilover manufacturers. I checked out their site, and the big plus is that they appear to offer a wide range of spring rates. However, various aspects as to build design and quality are unknown. They say they will match valving to the springs, at your request, but valving is not really that simple. Unless you could actually work directly with the company on designing a set for your car you will really be taking a crap shoot regarding the final product.
In the end the OP needs to heed their own words "Plus I don't want to compromise the handling of my car or make it worse than what it is now." Stick with tried and trued products, or live with the consequences.