Does vertical vs horizontal split in a base make a difference?

Hi,

I am considering the artisan divan base and noticed the pictures show a vertical split in the divan base. Is this the case and does this offer an advantage over the more common horizontal split? I'm looking for a base which will reduce roll together and roll off sensations. I would be using this with a firm edge latex topped springs/" class="">pocket spring mattress.

Many Thanks,
David