I tested various roms within the last few days - AOSP 5.1, CM 12.1, MIUI V5 4.12.5 (4.3), MIUI V6 5.3.27 (4.4), IUNI V3 (4.4), TencentOS (4.4), etc.
I came to the conclusion the bugs diminishing the essential functionality as we witness in Android L-based MIUI V6/V7 roms are possibly the intention from the developer. Slow speed when on wi-fi, unreliable GPS with a cyclic loss of signal, poor camera performance, etc.
Why? Because even the most obscure and shitty Chinese ROMs I tested offer this type of functionality that is precise and reliable despite other and more understandable bugs that are due to not enough capacity and time to correct them.
The essential factors like the ones described above are functional in all the roms but Android L-based MIUI V6/V7.
To all the guys who experience GPS related issues on Android 5-based MIUI 6/7 roms, especially the cyclic loss of signal - remove the Fleksy keyboard, uninstall it and if it doesn't help, try to uninstall any additional keyboards. Even the other apps may play a role, so the elimination techique should uncover the cause.