I have seen a good few lab x,s now and i rate them highly its just being lucky to get the right one.
It depends what you want the dog to do to decide what type you want but imo start with the 1st x then put the 1st x to a lurcher of your choice to start your own line,we did this by adding the 1st x lab to saluki lurcher types and they,v done the job well.Good luck