I've owned four different GS 300s since 2000 and I am also a professional engineer who has designed,developed and tested both pad materials and disc brakes for a living in the past. I'll leave you to judge if that makes my views relevant.
I have fitted EBC Greenstuff pads to all the Lexus cars I have owned at some stage (Marks 1, 2 and 3). First thing to say is that disc brakes are very sensitive to your specific driving style hence the variety of views we see in this forum.
If you drive your car hard, you may well need a more specialised pad material such as Redstuff to cope with the higher temperatures, albeit there is then every chance performance at lower temperatures will not be as good.
I get through a set of front pads in about 25k miles so I'm neither a hard nor a soft user - I find the Greenstuff pads excellent and a clear step up from standard Lexus fitments.
Braking is more consistent and predictable and there is no grab at low speed when cold/damp. I find they produce less dust than the standard fitments.
You should not expect more stopping force from a better pad, just more consistent performance across a wider range of operating conditions.
Second thing to understand is that brake pad development is essentially witchcraft with a brew of near random materials being put together until you get something that gives acceptable performance for most drivers - it's a crude compromise though and cannot suit all user conditions.
A major player such as Mintex will have thousands of different formulations and will test these in a new model until it finds brew that gives the best compromise for the allowed cost. There's no great science in this.
Third thing is that performance can also be sensitive to relatively small variations in the chemical composition of the disc metal itself, in some cases a few ppm of a trace element can change friction behaviour significantly - noone really knows why and I doubt if any one disc manufacturer is likely to be better than any other.in this respect.
Fourthly, light brake useage can generate a glaze on the disc that reduces performance, particularly on rear discs that do much less work when braking due to weight transfer. An "Italian tune-up" can quickly burn this off and I think that is also why the Greenstuff pads have a pink abrasive coating painted on the rubbing surface to "condition" the disc surface when first installed.
Finally on brake squeal, this is also a mystery in many respects where with apparently identical systems one will squeal and one will not. The shims that sit on the back of the pads are just there to stop squeal and I've always found that, by keeping those clean and using copper grease between them and on the edge of the pad abuttments, I've never had any brake squeal from Greenstuff pads, except, of course, when the wear indicators on the pad start to touch the disc.
Hope that helps. BTW, I have absolutely no conection with EBC.
