So, in going over all the Tyranid hoopla, I was struck with an idea. The biggest weakness to alot of the units seem to be Synapse. So I was thinking of using an old Third edition trick in a new way.
In previous editions, the enemy didn't always get a counter movement when you assaulted them. So it was important to choose when and where you assaulted a unit. It's one of those skills that is lots on alot of players who didn't play in previous editions. However, it may again prove useful.
Here's my generalized thought. Using a Hit and Run unit, pick an enemy unit near the edge of synapse range, assault the model farthest out of synapse try and keep as far back as you can, don't assault far into the unit. They will have to counter move towards you.
Once you have them pulled away, if you have gotten them out of Synapse, great, against a feeding unit, hit and run out, and make them move that much further out of synapse.
Otherwise, you wait till the end of the opponents assault phase, and hit them again if they are still in synapse.
Once the unit is out of Synapse range, they should be easier to deal with, you can pin or sweep the unit as you have available. This is also useful to get units away from the buff/debuff units like Tervigons and Hive Tyrants
Of course, that brings us to the biggest problem with the strategy, our only Hit and Run unit are Hellions, and Lords who join them don't gain the ability. So we may be wanting to keep another unit close to help back them up.