<<I have a Super ES with a bit over 400 hours on it.  It is on its second
set of brake pads (dutifully broken in per manufacturer's guidelines) and
the brakes seem to be working as well as they can. No air, solid pedals.
The brakes are the ones that came with the kit. Unfortunately, they don't
work as well as I would like them to>>

You're exactly right in my opinion - you always should be able to lock the
wheels.  I think this subject is more than trivial as I believe it is a
significant safety issue.  For example, if you land with one wheel locked -
or tire flat, or wheel off in soft dirt...you want to be able to easily
apply maximum braking to the other side.

The effort required to apply maximum braking (lock the wheels) depends on
the coefficient of friction and the "pedal ratio", or the ratio between the
master cylinder area, including the mechanical advantage, and the total area
of the wheel cylinders.  Some things are difficult to change others more
difficult.  Changing to a pad material that has a higher coefficient
probably isn't the answer as most high-coefficient materials also wear
faster and you're already complaining about excessive wear.  A metallic or
ceramic material might help, but I doubt it - and generally you trade pad
wear for rotor wear.  I assume you aren't complaining about a spongy pedal
as that will only increase pedal travel, not undermine brake effectiveness.
On the ES rudder cable stretch will feel like pedal compliance (are there
any testimonials out there for the effectiveness of gears on the pedal
shafts?).  There could be mechanical friction in the master cylinder, but
the linkage is pretty simple and not likely to bind up.  I don't know if
there are larger caliper piston diameters available, but the next step is to
reduce the diameter of the master cylinders or shorten the lever arm on the
pedals.  I am just getting to that stage of construction so am interested in
any comments from the experts and the experienced.

Gary Casey