Very nice photos, Dave! I'm glad you've seen some good blooms of this cv which can be very impressive.
You mention bud drop. I don't tolerate it myself nor wait to confirm the problem as heat or blame it on the cv. No doubt sometimes it is just heat or as in the case of some doubles it is a trait of the variety. However, in my experience it is far more often thrips and they can be easily gotten rid of. I spray spinosad as soon as I see any bud drop and more often than not am rewarded with lots of blooms in the weeks just after. Thrips are hard to see and it is easy to spray this low toxicity organic pesticide over the buds and tops of the stems. Do it more than once - 3 times with 5 days between each is ideal - and say good-bye to most bud drop. (The Gulf Coast states also have to contend with hibiscus gall midge but the symptoms and treatment are different - small buds turn bright yellow and drop).
The Greenlight company makes a version of spinosad that fits on the end of a hose and is good for those with a lot of outdoor hibiscus and also a concentrate that you mix yourself into your own sprayer. Get it and give it a go is my suggestion!
More details are at:
http://www.hiddenvalleynaturearts.com/acatalog/spinosadinfo.htmlCharlie