One video which inspired me to purchase tools and repair my own trikes was Bike Garage:
I ended up buying the DVD on ebay. However, like you said there are many available videos online which provide steps in repairing or changing out various parts of your trike. In regards to addmotor which you mentioned I haven't had any breakdowns in components other than changing out breakpads. However, other than their battery and controller (includes display) their components are common names such as Shimano, Bafang etc.
If a display or controller goes bad then your trike is virtually immobile electronically. I have had such good relations with Addmotor (through emails) that I am confident that they would respond to any problems in warranty or out of warranty. A controller or display are not going to break the bank nor is a bafang hub motor for that matter if you buy them outside of warranty. Batteries are expensive and even Evelo starts prorating their batteries for replacement after a time period and their extra battery prices for the Compass are insane at $800.
Let me address your options...I think you need to list better options, at least for me. Evelo Compass doesn't check any boxes for me other than warranty. Pedego doesn't check very many boxes other than service but I don't like their trike anyway because of the plastic basket and low speed. Mid-Motor doesn't do anything for me in fact I don't like them because if you have any failure in your chainring you're dead in the water-can't pedal and can't use power.
Of course I wouldn't purchase the Addmotor trikes at their current prices either (okay, maybe the M-330...outstanding trike---it checked all the boxes for me...I could ride that trike all day long...in fact I purchased a 2nd battery---an upgraded battery at $550). However, I was able to purchase Addmotor trikes at their "crowdfunded" entry prices which were excellent deals. I would do it again at those prices. So, yes, for me price matters. I would look for sales in any case.
Bafang motors have a low failure rate and are widely used and can easily be purchased. Shimano components--ditto. Controllers are generally not very expensive. If a trike checks all the boxes for you and it is cheaper with universal components then go for it over proprietary components and expensive trikes even with good customer service. I don't know anything about BMP but their rickshaw trike is intriguing if not over the top:
(Link Removed - No Longer Exists) If it checks all the boxes for you then you need to pull the trigger.
Maybe I have helped but if you have any questions let me know.
Dave