I've been running a 924S in SCCA ITS for 5 seasons, and many engines. I ran 3 of those seasons without driving the countershafts. Found it necessary to carry spare fuel rails, spare alternator pivot bolts, and a few other small items which would regularly fail or fall off. The engine was running on the stock DME with stock rev limit, and I tried to limit peak rpms to 6300 to avoid RUD (rapid unscheduled disassembly). I had been wanting to enter in endurance race series being run in this area, but the engine life expectancy was not up to it. I put some serious study into this over winter months and returned to "the books" from my engineering student days. The basics of reciprocating engine layouts show one of the inherent issues with inline 4 cyl. is the secondary vibrations caused by the flat (180 deg) crankshaft layout, where all reciprocating mass is reversing direction at the same time in the cycle. Without getting into the dynamic analysis here, all inline 4 cyl. engines suffer the issue, but the degree to which it becomes an issue is related to the reciprocating mass ratio to the non-dynamic components (everything else in the engine that is standing still). The reciprocating mass of the M44 engine is relatively high (one cause of the rod bearing problems I believe). So, armed with a theory (not much else to occupy oneself during the northeast winter months), and reasonably sure the HP loss due to those shafts was minimal, and really wanting to gain enough drivetrain life to dare enter an endurance race, (and understanding that the design engineers on that project were probably intellegent enough to have done a cost benefit analysis of the added countershaft system), I built an engine with the shafts operating as designed. The result of the experiment was I have not failed a component due to material fatigue since (2 seasons, many races). I have used a repaired fuel rail without a failure. Have not replaced the alternator bolt since.
So, believe what you will, I will run the countershafts as designed.