The r.skis that can be most easily slowed down on demand (both for
negotiating hills and for better resistance) w/o frying the wheels are
v2 aeros 150s. You have to lean over though to engage the speed
reducers, which personally I don't have a problem with.

150s are also good for bad pavement and for the occasions when you
have leaves/debris on the pavement e.g. after a recent rainstorm.

Note that inline skates in general are much better in rolling over
cracks/rocks because the 4 wheels in inlines essentially have no gaps
between them.