Which springs?

I'm drooling right now.

Have you used there product or had experience of it???

All I'm interested in are if it makes the vehicle more stable on the road, and what the end results on towing and carrying heavy loads?

I've no need for extra axle articulation, and I definitely do not want to lift the vehicle as that's just going to make it more unstable.

All I use it for is towing tractors to steam rally's and driving around flat grassy or muddy fields.

Had a fair old bit of weight in the back of mine (paving slabs)...cant honestly say how they compare to multi leaf in the respect.