One thing to watch is to make sure that the strong hive isn't getting ready to swarm when you do this. If they have swarm cells started when you make the split, you could end up losing a swarm from the strong hive after you split.
That's what happened to me last year. I saw that they were just starting to make queen cells, but thought I'd caught them in time. I cut out all the queen cells, or so I thought, and made sure that I left eggs in the box. Then I took the queen, along with a couple of frames and put them in a nuc. The weather got nasty for for a good while and I didn't get into them for a couple of weeks. When I did, I saw that that the big hive had swarmed.