RE: Upgraded my deck to improve performace, level 4 summoners and the cards I upgraded to match

I'm still in doubt about whether to upgrade my level 4 gold foil deck to level 5 or not. It would unlock so much more sweet abilities. :0)
I have all the commons and rares to do it, probably even most of the epics.
One thing that's holding me back is that it would make my gf dragon summoners useless. Another things is that I won't stand a bigger chance in the gold foil weekend tournaments, since my deck would still only be level 5, and not 6. So I'm still not sure if it would be worth it or not...