With more than 175 track days (including 80 races) on stock M96 engines, I think that your mechanic needs to reconsider his position.
I routinely get 60-80 hours of track time plus 10,000 miles of street driving out of a used (90K mile) engine before it finally fails.
I would recommend installing the X-51 baffle since its cheap and easy to install and will give you peace of mind. If you run sticky tires (R-compounds), then I'd recommend a deep sump with the horizontal baffle to go with the X-51 (see photo below).
Yes, I consider 2.5L M96 engines to be disposable, but only because the cost of parts and labor to professionally fully rebuild an engine ($7,500 to $10,000) far exceeds the cost of a decent used (salvage) engine (under $3,000). And no, there isn't a significant increase in engine life of a fully rebuilt engine vs a used engine under racing conditions.
Since I started racing, I don't baby my engine. I shift at redline and downshift at redline (and occasionally over-rev). Maintaining position is the name of the game.
