This is why I keep telling people to always go for higher-end mobo for mining.
You can never tell when you are up for more GPU, you are simply saving yourself for any future spending.
12 gpu slots motherboards aren't even that costly there is no good reason not to but them over 6 gpu motherboards.
The moment you buy your first three graphic cards you will want to add more gpu in a matter of months.
I do not buy a motherboard for 12 video cards for only one reason - I need to solve the problem with cooling. I use open cases, and the 5th video card in a row is already hot, and the sixth already has problems. And motherboards for 6 graphics cards are available in stock at all stores.
So you mean that splitting my rig into 2 ones, is my safest choice in the long term?