Typically what are you gaining on a two stroke with engine braking... It's not like a four stroke.
When down shifting I always blip the throttle, to both rev match and maybe give it a squirt of oil.
I certainly wouldn't be going down a big hill engine braking the whole way at high rpm on a two stroke. Nice blips on the throttle and a high gear to keep the RPMs down.
When it comes to competition bikes, well reliability is all out the question and if engine braking does even a fraction of slowing down then it's worth it, but for road going use I only engine brake in an emergency.