I have found that Optima batteries do not like high amperage recharging- it is very likely that your "topping off" between runs is finding false peaks. We lead-acid batteries don't care so much, but the acid-impregnated felt used in the Optimas care quite a bit about the amps/mins ratio. Also, be careful charging and discharging an Optima too quickly- their construction leads to very poor heat dissipation. Ten amps is OK, fourty is not.
I would check input voltage to the 6AL next time you have the engine spun up on the dyno- I have had spark fall apart when voltage drops below 11, and in a high-demand situation even closer to 12. As mentioned above, the MSD guys are very easy-going and easy to work with if there is any problem with the 6AL- they really have the customer service thing figured out.
Good luck!