1st gen cars the sedan sport, coupe & 350Z were all the same rate, just different drops.
I'm planning to check rates on 2nd gens.
It won't be right away though, especially with 370Zs just hitting the street.

Personally, I would definitely get sways first. They are cheaper and easier to install. Springs actually cost quite a bit when you consider install time, camber kit, alignment, premature shock wear, etc.

If I had an X and no one made F/R sets, I think it would definitely be worthwhile just to get the rears. But I think it probably is best to wait it out and hopefully someone will step up. How come someone can't send their bars in and have Hotchkis make a prototype off that and send both back to the user for fitting?

Rear only might be your only choice for the X
I'm not positive but I thing 1st gen X are still waiting.

I think it boils down to demand.
Outside of G35Driver, not many G35X drivers will be looking for sways.

Update on driving impressions:

From the limited amount of time I've driven today on the total CRAP roads in my area, I can say without a doubt that the ride is quite a bit more bumpy than with the stock bars. If you're expecting the same "plush" and "absorbant" ride from the stock suspension after these bars are installed, you're in for a rude awakening. The difference in ride quality is understandable if you look at how the sway bars interact with the lower control arms via the end links: the suspension arms move up/down, relaying the travel to the end links and eventually to the sway bars. Since the sway bars have less bend and play to them due to the beefier design, more of the road inconsistency is now placed on the springs/shocks than before. The fact that the original springs/shocks are designed for a more "luxury" or "GT" type of ride becomes evident, and how the spring rates are low and the shocks are too compliant.

It isn't like it isn't bearable, but there is a noticable difference. Just beware when you install them that you will want new springs/shocks in the future (at least I do).

Hmm So would it be possible for someone to contact Hotchkis and see if they would sell just the rears? How would the performance be with just rear sways? I mean I guess the rear won't roll as much but the front would still right? I don't have a spare Sway i can send in for hotchkis to do a prototype. I need to drive my car hahaha.

H&R's on the Stillen site are sold seperately, but they're quite pricey.

I need some coilovers now.....

On the site it says for the H&R sways :H&R SWAY BAR REAR 03-09 350Z INCL ROADSTER / 03-08 G35 INCL. SEDAN ADJUSTABLE 23MM

so according to them it fits the first gen sedans too? So the 1st gen Sways would fit our 2nd gen cars?!

I'm not sure, I just saw that this morning so I posted it. I would say to call them, and if it fits, to find out what the adjustibility range is.

What settings did you start out with?

The first.

First being softest?

After you've had them for a while, it's interesting to change up the settings.
You can really change the understeer/oversteer characteristics.
Take baby steps though.

Ya, outermost hole (softest).

I'm gonna drive around on the first hole about a week or so, then try the second hole. I'm fully expecting the ride to get worse the stiffer the rear is, but we'll see.

Man I miss my Bilsteins

I didn't notice a big difference in bumpiness as san~man described, but I am already lowered on Eibach springs with 19" wheels so it was already bumpier than stock (compared to the 08 Journey loaner car w/OEM 17" wheels that I drove).

Same here, I also have 19s and springs, so the ride seemed rougher because of those.