Hi.
Yes, the big Monsanto display on the MkI is my preference too.
The charging system is effective. If you wear it regularly, you can check it many times a day with no problem. If you wear it in-frequently, then it may struggle to keep up.
Of course this depends on what state the batteries are in. They don't last forever, and degrade in performance over time.
The MkI modules are reliable in my opinion. They have an encapsulated IC, and can almost always be brought back to life. There are a lot of discreet components which means you can swap out anything defective. Later models had everything integrated into an open wire-bonded IC (if something fails, the whole board is basically useless).
There are a few people around who can work on them.
Good luck.
Rgds,
Andrew.