I'm holding middle ground on all of this.
I see what Phil is pointing out and have much the same thoughts. I understand that by nature a racer will always look for improvements to the car whether they be there truly or not. That being said any change to an alum caliper could be considered an improvement etc. etc.
On the other hand I'm offering up some options that might be worth considering if you ultimately decide to go this way. Nothing that isn't being shared by another manufactures who appear to have a fine products.
I won't say for certain that the GP320 is an exact fit replacement for the LDs until I was to review the mount radius of each upright it would be fit to as it might also require a change in rotor OD by a small amount to fit...in which case as a buyer I'd balk too!
As for Derricks comments, I'll take them with a grain of salt. As a competitor in OW cars and crewing them for years I've become accustom to flipping pads to counter taper wear....certainly less costly than dedicated body halves. Stainless or steel pistons in alum calipers have been around for years and proven their worth. Deflection? Yeah, they all have that too. Granted some more than others, but last time I checked line pressure on an OW car was somewhere around 600psi tops?? I'm not feelin' the resultant design is going to be of much concern. The ICP stuff seems to do well and it's not a monster part either. The pad plates are certainly a good idea and I'll pass along the suggestion- they are found on most other models already.
In the end of all this I hope everyone finds some common ground and a solution they are happy with regardless of brand name. If anyone wants to speak with me, find me through the shop page or email. Until then I'm out. Best wishes to all.
Most if not all GP320 calipers are shipping today with ss bridge plates install. No confirmation of mount radius comparing this and LD on the same rotor OD however.