Gestalt 3 is an ALU bike with short chainstay and short wheelbase. It can accommodate up to 38c tire.
Expert is a lower quality Carbon bike with much longer frame and chainstay. And You can use the 40c tire with it.
Gestalt 3 has a SRAM groupset with one crankset. It is very tempting option. Expert uses standard Shimano 105 groupset.
Gestalt 3 should be much more nible and fun to ride but short chainstay may cause less stability especially on fast descends.
Expert is well know for its stability but also for less fun ride.
The price is very similar which begs the question if Gestalt 3 is not overpriced for its ALU frame?
The other question: will ALU Gestalt 3 (with 35c or 38c tire) offer enough comfort on rough roads?