Not much point in commenting...as apparently I know feck all.
In my view, the Neuspeed set-up is the best, for my driving style and really crappy roads I drive on (it also happens to ne totally neutral, and easy to power oversteer on the track) so I'd still suggest them.
Mine was a road car...on a road set up...driven in all weathers on all roads.
It was NOT a super stiff track car on coilovers...so uber large ARBs weren't on my agenda.
I would always go for a slightly larger rear bar over the front, to alter the chassis balance away from terminal understeer (yes, you'll still understeer whilst rolling less on equally uprated bars)...and I'd fit the smallest bars you can to get the results you want.
You need some transfer of weight to get the car to respond...
Too big and although great in the dry, hit a bump in the wet and you are understeering again.
If the ARBs are overly large (in my view) then you get no weight transfer or roll at all...which means you don't get the suspension geometry working properly (adding negative camber as it leans over) and you put all the stresses onto the outside front tyre...loading it right up.
One bump, rut or section of grit...you break traction and you've lost the grip.
Smaller ARBs give you more compliance.
Also consider:
ARBs are springs...they need controlling by the dampers.
Go too big, and you give the dampers more work to do.
Run very large ARBs on under-damped dampers and it's an accident looking for a suitable location to happen.
ARBs NEED to be matched to damper re-bound rates.
Large ARBs may be great on KW V3s where you can crank up the rebound damping...but I'd argue not so hot on fixed damping on a road car.
Everyone has their own views...
Their driving style, the roads they use, different springs/dampers etc...
But the Neuspeed set would be where my money would go...as of all the S3's I've driven (lots!) there has never been one any better than mine was chassis wise.
But, that's maybe just because it was set up for how I drive.
But hey, what do I know...