I grew up riding antiquated pitbikes (a Honda Trail 70, a Harley 100cc, and Hodaka 80cc). After those I got into street bikes for a bit in my teenage years. Those early dirt bikes and street bikes all had "normal" seat heights in that flat-footing it with both feet wasn't a problem.
Well, a few years later I got the dirt bug again and bough my first "real" dirtbike, a well-used 1986 CR125. Let me tell ya, it was way different than anything I'd ever ridden before. Tall, skinny, pipey, etc. I never thought I'd feel comfortable riding it the first few times I took it out, but it wasn't a week or two before I was whipping it around like like the old Hodaka.
As with anything else it just takes a little time to get accustomed to the differences. Trust me, the additional power on tap will more than make up for having to learn to adapt to the increased height.