Kinda Noobish Question

I'm currently running a 6.0 Custom Rom, It's SinLess 9.1.0 to be exact.

My question is this. Would it be okay to flash a 5.1.1 Rom now(I want to try the Dirty Unicorns build), since I'm on 6.0. Or can I only flash 6.0 Roms? I just got this phone, and I came from the ATT Note 4 which had a locked bootloader. I know a little bit about custom roms and flashing from previous phones, but not as much as I'd like to know. Any help would be greatly appreciated, thank you.

AnTuTu note edge vs. Z5 Quick benchmark. Kinda disappointing

I bought my Xperia z5 to replace a Note edge that I tried getting fixed after water damage. After getting the z5, I got the Edge fixed a second time and edge works as good as new. Ran AnTuTu....... Scores of the z5 are not as great a difference vs. The note edge. I'm running the z5 on stock cause there is no community roms or root yet. The note edge is running Tekexodus 4.2 extreme dev edition with the permissive low lying fruit kernel. Besides the overheating issue of the 810, which isn't an issue in the z5, is performance increase supposed to be this little or is it the power of custom roms and kernels?

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