Looks line they would both function, Todd.
However, I understand your concern. When I
replaced my failed brake line with a stainless steel braided hose (from
Van's aircraft) it turned out to be a -4 line whereas my other gear has
a -3 brake line. Both brakes function and stop the aircraft, however,
there is a distinctive difference in the feel of the two brakes. The
-3 side has almost a rock-solid feel, the -4 side has a slight bit of
give upon initial depression - actually you have to go down on the toe
just a bit more on that side.
My guess is that the greatly increased volume
of the -4 line over the -3 line causes more pedal movement on the -4
side to build up the same amount of brake line pressure. I really
don't like the two different feels and have a new -3 line to replace
the -4 line.
My guess is your two different parts would
probably push on the pad with the same force - however, from what I
have seen I would think that the one with the recessed top would be
likely to accumulate more crude that the other one. On the other
hand, there could be a good technical reason for the recess - like
perhaps less surface area to transmit heat from pad to hydraulic fluid
- now that's one I could relate to. That's the only reasons I can
think of why the difference.
IN any case, I think I would prefer to have
both the same - probably doesn't matter which on you go with.
Ed A