For me, an adjustable panhard is more a bling thing than a performance mod. The poly bushes do make the rear end feel a bit more solid but that the only performance enhancement it has over stock. The reason I got it (besides only being 100 bucks) was to allow the fine adjustments to fit wide wheels with low offsets.
A problem I had in the blue car with its stock panhard was that the combination of wide wheels and excessivly low ride height, the right rear tire would scrub on the guard on even minor bumps. This was fixed by bashing the inner lip flat and running thinner tires. But it would have been better to just shift the diff across about 2mm and it would have been fine.