Frank,

Optimal launch conditions are best for all playing conditions regardless of altitude.

Going off of your launch monitor numbers, your launch is optimum but you spin is a little high.  To max out your distance off the tee you would want to get your spin down to 2200-2500.  You may try the D3 model.  You spin should drop 300-400 rpms.  Remember that the head and the loft of the club is the engine of the club.  The shaft is a feel and fine tuning mechanism.

See a fitting specialist in your area that can help you get dialed in.  The FittingWorks website will guide you to the right place.

Kevin Lozares

How does the high altitude affect ball flight there?

The ball wont move as much (Draw or Fade) and goes further.  So you'll hit it straighter and further than you would at sea level.

I guess that makes sense. Thanks

I recently taught a Titleist cub fitting seminar to the Titleist staff pros in Denver.  They informed me that they look for a little more spin than usual since spin decay happens quicker at higher altitude. Best to find a good fitter that fits outdoors, uses a launch monitor and also uses Pro V 1 balls to fit with.

steve ball, PGA
Senior Consultant to Titleist Club fitting

It shouldn't matter, but you'll notice about a 10%ish distance increase vs Sea Level.  I used to live in Breckenridge  (9,500+ ft) and then moved to Costal Massachusetts so my 10% loss might be a bit inflated.  I have to say that extra distance was nice, but you’ll love your 910 as soon as you get it.