I would avoid going more than 10:1 compression on a everyday rider. You need to consider that even the premium gas is not what it used to be. Do you always want to have fuel additives in your back pocket? Pinging or Detonation is bad on wristpins/bearings etc..going with 9.75:1 woulld be a good compromise. I have bee on many major bike events. Sturgis, Daytona, Bike Blues &BBQ and LoneStar rallies. Some gas stations had completly run out of premium gas! and your motor will run hotter. But being a EVO motor you will probably be OK. Be glad you have a EVO and not a TC motor. Alot of Harley shops would be out of busseness if they had not made the TC motors. EVOs are alot more durable, less money to get good HP gains, run cooler. The FI motors just dont sound a good a the carb motors. A few more CI you may want a different cam. just make sure it turns on at the rpm you want ex: 2800 -3200 rpm. The EV 27 has fast ramps that it harder on you lifters and other valve train parts.
Just my two cents,
Ltank