First place I trained had an older instructor: older guy, close to 50, 4th degree black belt who had trained under Marcelo Behring... Very old school, VT oriented jiu-jitsu... Had a TON of knowledge and taught me heel hooks back in 96-97.
He had already had a stroke, had really bad knees and back, so he never rolled hard... At most he'd get a student he trusted and ask the guy to pass his guard, or get out of side control.
He would, however, pay attention to you rolling and if he noticed something wrong (a posture, move or missed opportunity), he'd stop you right then and there and showed you something that would work for you, based on your attributes, style and body type.
20+ years later I still use those techniques and remember lessons and sayings from this guy.
Current instructor rolls with almost everyone at every single session, is 100% sport bjj oriented, keeps up to date with the latest trends, competitors, shares videos with the students.
He rolls hard and is pretty honest about rolling with us upper belts for HIS benefit - whenever we talk about a particular roll, he will mostly ask me about something he did, and only sometimes offer advice or correct me on something he spotted...
He's more than eager to work with me, however, if I'm working on a particular concept... I showed him some leglock stuff from Lachlan, for example, and he took the whole class to understand it's and drill it with me.
BOTH instructors are awesome in their own ways and I wish I had the privilege of having both around.