7% would be around 7-11 fewer beats per minute - I'm not sure that equates to 7% less effort. There's a good chance that would put you in a lower HRZ too.
Personally emtbs give me 100% more exercise than analogue bikes because I don't have one :)
I bought a pair on ebay for £15 and they're pretty fast although not excessively dark, they're polarised too. I use them in the winter mainly - in summer I wear Flack Jacket regular sunnies and look good as I ride semi-blind into the woods.
I use eMTB almost exclusively - it's adaptive to your input and feels right to me. If I'm cruising the motor's cruising and if I'm sweating I want the motor to sweat too.
Yes - as mentioned above, @Doomanic posted a guide on how to align the top and bottom battery terminals which solved the issue for me and several others I believe.
If it were an asset in a business, it would likely be written down at 2% per month from the price you paid. Prevailing market conditions and asset condition would determine if you win or lose against the depreciated value at the point of sale.
Bikes are in short supply so you could be lucky.
I would suggest it's already too late in 2020 to be concerned about personal data, unless you've been extremely cautious over tlhe last 10 years and kept your details away from Apple, Google, Samsung etc. they already have it. Governments all have access to your phone data (Edward Snowden...
If your not struggling for leg power you can drop your seatpost to lower your centre of gravity, this will help keeping the front down and the rear gripping but at the expense of pedalling efficiency /comfort.
This counter intuitive phenomenon is true for internal combustion engines too. It's more economical to power up a hill and get it over with as soon as possible, using maximum power for a minimal time rather than the green band for longer.