The main benefits are M.2 card support, USB 3.1, and more PCIe lanes to keep everything running at PCIe 3.0 speeds. That's probably why they say it's worth the upgrade. Extra features for future usage. It will depend on whether or not you are going to invest in devices that use those features though.
Me personally I'm eying an upgrade to move away from the mATX board I've been on since 2012. It's a great motherboard but it cramps my devices together and I get some higher than average temperatures from my 2nd 970 because it's starved for air. I can piece this system back together for some other usage at that point.
Are those the dual-fan "twin-frozr" type cards, or the reference-design with the barrel fan?
If the case is getting good intake, try removing the PCI slot-covers above each card. It might only be worth a couple C degrees, but you could start there. If the case is pressurized, there should be no down-side to these extra "vents."
Yeah, I game casually, but don't really beat the crap out of it. I may just go for the GPU upgrade...again.