With the old-style crossings the entire diamond section was dead to prevent center-rail rollers from shorting to the running rails and vice versa. The dead sections aren't a problem as long as you have two center-rail pickups both working well and not too close together. It would be an issue with shallower crossing angles which would create a longer diamond section.
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In this FasTrack crossing pic the yellow-colored running rails are all dead, otherwise the center-rail pickups could short to the running rails. Like the 020x crossings, this can be a problem for some 4-wheel locos, especially if they have a traction tire and if they don't sit square on all four wheels and if rails aren't too clean. Point being, it's not just the dead section of center rail that might be an issue - the running rails are dead for that part also.
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Last pic shows a home-made 67-degree crossing made from a solid hunk of plastic. The entire diamond portion is non-conductive and trains run OK. (The yellowed plastic is showing where the wheels wore through the gray paint .)
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So for the original question, minor modification can isolate the FasTrack routes and the center-rail portion inside the diamond can be left dead and will probably not be a problem. Apologies for any redundancies to the previous posts.