My wife and I have been getting very interesting results with Dracul and it looks to us like there is a lot of variation depending on exactly what he is fighting. 1 recruit can take 60+ cavalry but only a handful of bowmen for example. He is definitely tougher in some camps but not so much in others.
To be honest though we have not done the hard yards of lots of record keeping and working with the calculator so our impressions might be a little off. But I did reorganize some adventures where I use multiple waves and I didn't get as much difference in losses by using him in waves as I was expecting.
I'm sure someone with post some definitive information about what is making the difference from time to time. We figure it's that he doesn't have "attacks weakest" and we're not always sure what order things will get hit in a round - or something like that.