i read lot of times that it is safe to update sysNAND, so lets say i am on 9.2 atm. you say it is safe to update to 10.7 sysNAND o.O ..
would my GW emuNAND still work? (but then again i dont need sysNAND as i only use emuNAND so.. i dont know what the benefit for me would be updating my sysNAND).
No, GW emunand would not work anymore.
You need to be on 9.0-9.2 to use it, even with the UpdatedSysnand mode.
To answer properly, first of all, I don't really see the point of using Gateway and Arm9LoaderHax (yes, really, it is nearly the same as the Mset exploit, instead of using System Settings you may use Homebrew Launcher but basically, same thing).
Then, now we can restore sysnand as we want, even if we mess with it, we can just boot Decrypt9 and restore a backup. Using sysnand is as safe as using emunand. And now, using AuReiNand (but also with CakesFW), you can update sysnand and use the system "normally". The main point of using sysnand is that you don't have to install GBA games two times for example or you don't have to come back to sysnand after leaving a GBA game otherwise it won't save...
It's just way more convenient because the system act as it should act, the only difference is sig check patches.
But if you want to stick with emunand, just don't update sysnand, there is no point to do it.