Re: How does Aikido compare to Aiki-Jujutsu?
A couple of points:
One of my students did his shodan with Paul Barker in 2002. He has since moved around and practiced in other places. The good side is that he has excellent movement and techniques and good basics. The bad side is organisational - in order to promote him to nidan (long overdue) I first had to recommend him for shodan aikikai (with relevant payment of fees and membership) in January, and will be able to recommend him for nidan at the end of this year - grading politics is a pain, but worth being aware of - depending on what you want to do with said grades (and it becomes important when you start having your own students - what system will you be plugging them in to?)
Regarding building up a sweat during practice - this varies significantly in the style involved. If that is something you like, then for example a Tissier sensei associated dojo is likely to give you an excellent workout! As it was put to me after I had taught a class in an affiliated dojo "you work on relaxation from the start - we work on it when you are exhausted from practice..."
It takes all sorts, and I would recommend regular seminars and/or visits to other dojos to ensure you get a good overview of what's on offer.
Enjoy your search!