That doesn't seem too bad height wise.  Mine is about the same in the back but maybe 1/2" higher in the front.  So height shouldn't be an issue.
 
You've said you got them new so, have they been this bad the entire time?
  Soft settings IMO are too soft, they're softer than the 94 Bathurst I sometimes drive which has stock suspension in it.  Its almost like bumps are in slow mo.  So I'm no convinced a softer spring rate is the answer for you.  Plenty of people have run these and the only general compliant is "they're too soft".  I imagine something else would be at fault.
 
Maybe an odd question but where are you?  I'd be more than happy to take you for a cruise in mine to compare seeing as our set ups are so similar to see what you think.

I had tien SS I bought new and fitted to an MR2. I found them quiet stiff aswell. I liked it though, the car definately felt better then the stock suspension. It was very harsh over bumps in that you feel every bump on the road even on the softest setting. This was on a GEN1 however, not a GEN3 suspension setup. I found wet driving quite dangerous aswell. I'm not sure if its the spring rate or gasing of the shocks that make them so stiff. It feels liek the rebound rate is set really high.

I agree with getting it professionally setup before spending $$ changing to new parts. If you wanna change the spring rates it's best to re-valve the shock to suit as well. What is your current wheel alignment specs as well as tyre widths?
 
Based off months of research, I decided on getting the RSR Race springs with Koni Yellows for road/track, 85:15. I believed this was the ultimate budget spring strut combo for road/track short of custom springs and comparable maybe only to H&R springs. Total spent was $1100 on parts, new strut inserts but 2nd hand springs (rare).
Reason I decided for springs/strut over coilovers: It was either this, HSDs or KW V3s. I didn't want too many adjusters probably because I suck at it lol (plus too focused on learning to drive haha) and I didn't have 2.5k.
 
On the road, my car is fantastic, a bit on the stiffer side of things but thanks to Koni's, my ride did not increase too much in harshness compared to stock spring/strut (late model springs, new KYB stock inserts). If only I could show you tomorrow at the VIC cruise (in 6 hours, I should be sleeping hehe). It eliminated a decent amount of roll but the most significant improvement I liked was, with lack of techy lingo, "faster rebound". Stock struts would wander a bit over high speed bumps on the sweepers *cough* freeway ramp *cough* but the koni/rsr reaction time made me more confident driving. Only compliant, lack of bump adjustment, but I'm still learning.
 
Quick track review:
Short story: The car was still quite balanced vs stock, more so thanks to stiffer rear spring rate bias dialling out the understeer. It still understeers to my dismay but much less than before and I can actually power oversteer on exit. Body roll has significantly improved but still too much for my liking. I guess there's only so far spring/struts can take you and no thanks to limited MR2 aftermarket selection.
Shorter story: Should've gotten coilovers for the grip levels of A048s and my driving style.
 
For getting rid of understeer, I was thinking of removing my front sway bar next track day.
 
Just my 20c, finding the best setup is hard because we all have different driving styles...

Thanks for all the replies again guys, sorry for the late reply, been away in Echuca for a wedding.

I would be pretty keen to take a ride in someone else's car to compare my own setup with a similar setup car and also a car setup with spring/strut, to see if I would like to go down the spring/strut route.

I'm going away for a bit, but I should be back in about 6 weeks. So I'd be keen sometime after then.

Cheers guys

Could be a difference here as well between Jap spec or the Aussie spec ones. AFAIK, set aussie ones up differently.

The Jap and Aussie Super Street ones have the same spring rate