There are good and pretty mature drivers for all new GPUs so there should not be a problem. Just follow good old procedures, Before taking old one out, cleanly uninstall old drivers with DDU from safe mode and only than change card. Prepare new drivers in advance and you'll be good to go.
For that system, you won't get too much with stronger graphic card, eventually Rx 480 or GTX 1070 just so you get rid of dual GPUs and have better performance in non- SLI games.
So I'M assuming any new updates will not happen untill after labor day since there needs several bug fixes.
Canary build is now 14916. Almost 3 weeks since 14905 was released. I expect a release this week. If there are bugs that need to be squashed its not in Preview Build but the current 14393 (1607) series.
There might be some weird logics behind this thought of you guys "No builds this week because Monday next week is Labor Day", but if there is it totally escapes me.
Anyway, in the mean time:
For those browsing forums with mobile app and not seeing the tweet above:
Dona Sarkar @donasarkar 5m
5 minutes ago
Oh hi there, FlightOps. Everyone got coffee? We have stuff to do this morning for the #WindowsInsiders!
Funny isn't it! Labor Day this coming Monday, yet we got a new buildDona Sarkar @donasarkar 2m
2 minutes ago
Hey #WindowsInsiders: FlightOps is well caffeinated today. We are releasing build 14915 for PC+Mobile to Fast Ring:
Checked just 5 minutes ago, nothing, checked now and it's coming down. What do you know, so it was exactly at 7PM: