The new Master Volume screen reflecting the individual output volumes for Main Output, Monitor Output, Direct Output, Headphone Output, SPDIF has been introduced to hopefully avoid the misunderstanding of your first paragraph:
The 0-10 scale of Master Volume had never been absolute - consequently not in dB - and yes, it's completely normal, that your Profiler is quieter at 8 than another at 3! The volumes of the outputs linked to Master Volume can all be at different levels and those are relevant.
If you both are owning powered Profilers you need to compare Monitor Output Volume and Power Amp Boost, both in dB. Other factors could be the level of Volume Pedal or the resistance of your cabinets. Perhaps one is running at 4 and the other at 16 Ohm.