I know some of the DIY kits do a removable battery.
I’m biased toward front-loaded bikes because I like to have eyes on the cargo and the weight distribution is better. I’m very biased toward sled-style bullit bikes but after seeing @karl_dandleton and @spaghetti with their Crust forks, I would put that in my top considerations.
When I was at lunch I saw a guy ride by on what looked like a Bullitt, but it had like a truss frame cargo area and looked like much smaller tubing overall.
Shop Info - Bike Swift is a great Seattle LBS that is expert in this stuff and also tight with Grintech in Canada
Electric Bike Inheritance Fee: $99
After initial 5-10 minute diagnostic fee, this is our charge for working on the electric assist system of any non-Bike Swift purchased electric bike or conversion kit. It is a 1-time fee. Labor and parts are charged in addition to this fee. After this fee is charged, you are one of our customers with all the support and care that entails!
I haven’t felt the need to upgrade to the ep8. My anecdotal experience is that it’s quieter and smoother. The e6100 carries me and 150lb of stuff up a 2 mile hill with no wish to go any faster or to work less hard.