First off, I've never owned any clones, so my experience is only with the real thing. I'm a bit of a purist (not a snob, I swear!) in that regard. If you cruise the HK boards, you'll see that the track record of clones is not great. The .308 clones are iffy depending on the builder, and the 9mm clones seem to be even more troublesome. The .223 clones are new to the market, but the initial reviews are also a bit iffy.
I've got just about 0 gunsmithing skills, but I'll say this much, the HK series is really tough to work with. Personally, there are only a few folks that I would trust to do HK work (especially any barrelling), and those fellas have been doing it for years. I don't mean that as an insult, I'm just saying that it seems like there are only a few guys capable of building a fully functional HK. Hell, the guys at C&S Metall-Werkes build MGs all the time, but they won't touch an HK. Of course if you are up for a challenge and don't mind tinkering, I say go for it. But if you want a 100% functional gun out of the box, you should buy the real thing (HK German) or have a good builder put a clone together with good parts. I can give you a list of guys if you are interested...
.308 HKs are great guns. Accuracy was very good and mine never once malfunctioned on me. Prices for parts used to be pretty high (and hard to find) but lately the parts are fairly abundant and sometimes reasonably priced. Hell the mags are under $5 now! I remember paying $50 for 20rd steel mags when I first got the gun! Also there are some good upgrade parts out there for the .308s.
The negatives of HKs system... Over priced (for the real thing) due to the import bans and the weird cult following. A bit heavier than some other .308s. A bitch to clean. Tear up brass and fling them really far (a big negative if you reload, or to the guy shooting next to you). Not the most ambi. system. No bolt hold open (I'm spoiled by ARs). Also, I don't know if I'd take one into combat (I will never have to, but this is just food for thought). I've met some German and an ex-Iranian soldiers that swear by the G3 (and have used them in combat), but personally I'd be afraid that any dent to the stamped receiver would put the thing out of action easily. This isn't an AK with loose tolerances...
On to the .223 HKs. Well, that was the HK that I shot the LEAST and sold very quickly. Take all the negatives of the .308 HKs, carry them over to the .223, and you get an overpriced .223 that is MUCH heavier than any other .223 on the market. It is still accurate and reliable, but that all it's got going for it.
Also, since there are less .223s out there (unlike all the G3 kits that have been imported) parts are much more expensive and harder to find. Mags are also expensive. I really liked the steel 25rd mags, but they were about $70 each. Alum. 20rd mags are about the same but for some reason alum. 40rd mags can be found for $40. I never liked the 40rds mags because they stick out too far for my tastes, but YMMV.
In a nutshell, the HK93 is a good rifle, BUT it is too expensive and too heavy for a .223. Not as fun as the other .223s out there. The only reason I would buy one again would be for a safe queen, or if I was going to have it cut down into an HK53 (the .223 carbine).
If you REALLY are looking for a .223, go with an AR. I don't know who you have run into, but I rarely encounter any problems with my ARs. Other than AR10s or franken-guns, I have rarely seen any other folks with AR problems. Not to insult the AK crowd, but I usually see more AKs jam at the range than I see AR choke. I could praise the AR system all day long, but this is AR15.com, so you can easily find that info here.
Hope this helps.