I am new to the E-Bike thing and am getting older and my back wants me to consider some kind of e-bike to conserve my energy levels.

I have a 2004 Specialized Crossroads Hybrid with a 7 speed, 11/28 cassette, 700cc X 32 tires. My bottom bracket is listed as having a square taper 68mm shell, 113mm spindle, sealed cartridge. I use this bike for around town stuff, shopping, etc. I am considering either a conversion kit or buying a E-bike.

I am looking at a Juiced Rip Current (750 Watts) with 52V/21Ah + 8A charger for $2400.00. I like the features of the bike considering what you get for the money. Link: https://cdn.shopify.com/s/files/1/10...g?v=1519592884. There is a full spec sheet download in the same link: https://drive.google.com/file/d/1B5T...cfaetbZiw/view

The majority of the reviews have been good/positive. This is a rear hub driven fat bike. Some say the rear hub motors aren't that great for climbing hills? But I've seen YouTube videos showing otherwise, so? I like the style and options on this bike and its ready to roll! I like the idea of the fat tires for comfort dampening the bumps and unexpected jolts from road imperfections, sidewalk curbs, bridge abutments, etc.

I live in Florida, so I ride on mostly flat land/hard paved roads for around town shopping and a few Interstate bridges to go over. No off road stuff as my bikes are not suited for that. If I have no hills to climb, so I presume the rear hub bike choice shouldn't be a problem for me in my area.

I have been looking at front/rear hub and mid-mount conversion kits as an option. The available online info is a bit confusing, but the reading I have done so far seems to lean in favor of mid-drive kits.

I've looked on e-bay for kits, they have many front/rear and mid-drive kits available. One I looked at: A rear hub kit for a 700cc tire from Calibike.com: https://www.ebay.com/itm/3000W-5000w...53.m1438.l2649 .... includes 72v18r triangle battery. Not sure how this would work on my bike or if its overkill? But seems like a good value for the money, $1,550.00.

I've looked at the Bafang mid-drive kits available from Luna.com. Bafang BBSHD 1000W Mid Drive Kitfor $679.00.

If I add the required options to the Bafang motor kit, electronic gadgets, tools, battery, charger, etc., the total comes to approximately $1932.95 or close to $2000. The bike I linked above is all assembled and ready to go is $2400, a $467.05 difference. A difference I don't mind paying if I can't get needed support if and when I need it.
I've been pumping the Specialized bike for 14 years now, so a new e-ride would be refreshing.Thanks, sumbikerguy!