Polyurethane bushes good or bad

We have the Blue Polybush in a couple of Land Rover's on the farm. So far so good.

When I say not all poly bush are equal. Is that in the case of Polybush, they offer 3 different grades. Blue is soft, Orange similar to OEM rubber and Red for stiff/performance.

Super Pro also use varying grades, but don't normally tell you much about it.

Lots of cheaper ones could be anything, some will be good and some likely terrible.

From my experience, if they're cheaper than the OEM style replacement bushes, they're probably rubbish. 
Then again, I haven't used them for many years, general no-name brand quality may have improved. 
I personally don't see any advantage in using them over OEM style in my Jimny, if anything I would want more flexibility, but your application is different to mine. 
My 2008 Jimny (nearly 200k kms) is still on all original bushes apart from castor correction in the front and the shock bushes. The original bushes I pulled from the radius arms to correct the castor are still sitting on my bench good as new. 

Years ago I ran poly bushes on a sport hatch (a 1992 Suzuki Swift), the handling was absolutely amazing, ride comfort was non existent, and for a vehicle that saw only street use, I'd say the wear rate was horrendous, despite the fact that the bushes were frequently cleaned & lubricated with the correct grease to get rid of the constant squeaking.

My needs have since changed and I can't see myself using poly bushes in the future.

You get what you pay for like with all items.
My bad experience are with the cheap ones on the SJ with many bushings in the ends of the leaf springs and shackles. 6 bushing halves on each spring.
I like soft and flexy so for me there is no point in it.

I f you can choose the Shore hardness I guess the original rubber is 70 shore or most likely around that. For any significant noticable difference in stiffness hardness you must up at 90 I guess or about 20 shore.

We have this test piece at work. 

 

Only times , we have used them , are on the caster correction, for the front arms , no issues there, but wouldn't use them , else where

I was our at the weekend with the boys and one of the rs fords was saying he was fully polyurethane bushes and honestly notwithstanding his rather silly ride height he was jiggling about something rotten on what I considered to be decent tarmac, it was bad enough to be seen from outside. Increasingly I'm just not feeling it or rather I'd prefer not to have my teeth vibrating out of my head.