Most of G-Force's hi/lo tapes are pretty dancy, but not terribly intense. When I'm learning their hi/lo routines it's definitely a struggle to stay in my target heart rate zone. Once I know the routine I can push myself in certain parts of the workout to keep my heart rate up. I don't know your situation but I personally carry a lot of extra weight, so if anything I can usually stay in my THRZ even when those of a more "normal" weight can't. So if you are slimmer/more fit than me, you may find their hi/lo to be not very challenging (intensity-wise) at all.
I LOOOOOOVE all of their step tapes, especially the two latest ones, Super Step and Cardio Step. SS in particular has less teaching and more intensity. And they are such fun instructors...I just love 'em.
Hope that helps!