Ok what is the car being used for and why do you think the standard MGB kit is not up to the job?
None of the kits alter the geometry; a spring is a spring however it is packaged so in reality after all the hype what you are getting over the standard setup is a more modern damper.
Once you have the correct spring for your application an adjustable damper is simply dialled in to arrest spring oscillation, to soft, it bounces down the road. Set them to hard and the car jacks down to the bump stops, over simplifying but I hope it makes sense and is helpful.
Regards Mel.

Mel,

Firstly - I remember the LA dampers leaking on a regular basis, but have since found out that was more to do with 'recon dampers' being a bit of a con - so I could just get new dampers.

I also understand that the MGB suspension is designed for cross ply tyres and as I am running wider radials the suspension would benefit from negative camber and reduced castor angle.

The Hoyle kit, the MGOC Evo 3 kit, the FL kit and the old Ron Hopkinson - now Moss Bilstein kit all move the damper outboard which improves the damper's effectiveness, the Hoyle kit also move the spring outboard allowing a reduced spring rate because the lever effect of the lower arm against the spring is reduced.

Of course all manufacturers either claim - "ours is the best technically" - or our's is the best value".

With regards to using the car - I'm only going to lightly tweak the V8 - lighten crank, balance, warm cam and Peter Burgess heads - so about 225ish bhp - then initially open road blasts, then occasional track days

So I wanted to hear from people who had driven the standard suspension and then modified and could give honest feedback - ideally covering all the bases - what actually changed - for/better or worse, did the new suspension last or fall apart - was it worth the change ?

Hi Malc, I did post last night while away from home but it looks like it has disappeared into the ether.
I only had a quick look at the kits and you have obviously done some research.
I have looked again paying attention to your intended use and accept that for any track use the suspension needs upgrading, how to do it and how much you need to spend to get the desired results is the problem that needs resolving. Lets look at what they offer.
1- Frontline.
Basically an uprated damper kit. If there is any weight reduction I doubt there is any worthwhile unsprung reduction where it matters.
2- Moss.
Plenty of waffle on the link with no detail. Looks good but this

. The road springs are retained by collars on the dampers allowing the spring and damper to work together..

Means nothing.
3- Hoyle.
From an engineering point I like it but IMHO it misleads.

the springs are positioned closer to the wheel enabling a much softer spring to be used

And you appear to have misunderstood this sales speak.

the Hoyle kit also move the spring outboard allowing a reduced spring rate because the lever effect of the lower arm against the spring is reduced.

As the sprung to unsprung weight has remained the same the spring has effectively remained the same the same. You may understand that but lets explore the sales speak.
Because the spring is further out it compresses more lets say twice as much (to explain). If the original spring was 100lb per inch and 1inch wheel movement compressed it ½inch it is seen as a 50lb per inch spring. Moving it out so as 1 inch of wheel movement equals 1 inch of spring movement to keep equilibrium you need a spring rate of 50lb per inch and nothing has changed.
It also states

and together with high quality damper units results in a more supple suspension

So we are back to the main improvement the damper.
4- MGOC
Uprated damper with camber and castor mods.
5-Uprated damper.

Im still of the opinion that for the money the main improvement comes from the damper.
Lets address camber it can be modified to suit by elongating the outer bottom wishbone hole and welding washers on in the desired position.
As for castor I think it depends on your driver feedback and is also easily altered by packing the subframe.
Anti roll bars?

I have tried to correct my last post as it looks garbled, the quotes were highlighted when posted. I have now tried 3 times with different browsers to post, all rejected as spam.