Run Krypton 17 Via sd card. That wont Brick your box. Both Versions on the 1 box.
Than you - much appreciated.
If you upgrade to the same variant - i.e. MXQ, HD18Q or m201d - you shouldn't brick your device. As advised above by Kostaman, you can always try running from an SD card first or if you already do, try a different card for LE 8. I have to admit that nowadays I test S805 builds very briefly as I consider them very mature.
Actually the only change that could affect this was between 8.0.0b and 8.0.0g. You can try to bump your GPU speed by echo 4 > /sys/class/mpgpu/cur_freq.
Thank you for the answers and advice - much appreciated.