Lots to think about. I also like the battery mounting. Right now Bacchetta and Terra Cycle are out of the mounts for a Giro.

(Spent a couple of hours on a flat empty parking lot today practicing starts and stops. Time well spent.)
 

I decided to do the Tongsheng TSDZ2 mid-drive assist on my 2006 Corsa. I ordered the kit from eco bike with the extension cable to the battery:
https://www.eco-ebike.com/collections/tongsheng-tsdz2/products/tsdz2-w-xh-18-torque-sensing-pedal-assist?variant=12702254170194
 
I ordered a 52V 13Ah battery from Amazon. I ordered two things from Bacchetta: X-Eyed front brake and the E-bike battery mount by Terracycle. Thank you Mike Wilkerson for the help and prompt shipment! I also put on some tougher tires for the multi-use paths I sometimes ride.
 
On my first test ride, I set the Tongsheng on its lowest setting (eco) and took it on a 12 mile good ride. I want to get a work out on rides, and I had a good sweat going by the time I got back. I'm recovering from a knee injury, so I like having the extra power if I need it on hills, but I want to work too. The harder I pedal, the more extra power the Tongsheng provides. It is like having extra strong legs. It is fairly quiet but not completely silent like some e-bikes with Bosch or Shimano motors. From what I've read, the Bafang motor is a little quieter too.

Anyway, it is reasonably quiet and made for an enjoyable ride. Given the geometry of the Bacchetta handlebars, the shifter grip (which replaces your front derailleur) fits perfectly but it is at an awkward angle for reading the screen. I didn't bother to hook up the speed sensor since I will continue to use my Garmin GPS. I will only use it to shift up or down (there are 4 levels of assist).

Note that after this conversion, the Corsa has become a 9 speed bike, so I put in a 11-36 cassette on the back to have easier gears for climbing (I already had a long cage derailleur to support a bigger cassette). The range is variable and I don't know how far I'll be able to go. Some of the numbers with a 52W 13Ah battery range from like 30 miles (if you ride it like an electric moped) to 100 miles (if you ride it in eco mode and perhaps even turn it off once in a while on flats or slight downhills). I'll update this thread when the snow melts and I get a chance to go on a long ride.
 

Note: if any of you are having trouble logging into the bacchetta forum, use FireFox. I've found that Chrome fails whenever I try to log in.
 
Update on 12/21/2020:
I've done a couple decent rides of about 20 miles with 1300 feet of climbing and 21.5 miles with 1200 feet of climbing, and I am still very happy with the Tongsheng and other modifications. The barely audible motor sound disappears if there is any wind or traffic noise. At the end of the rides, the battery indicated about 75% left (although I'm not sure how accurate it is). On flats, I generally switch it to assist 0 (none) and then my Corsa feels like it always has, which is to say that it is great. When I have a climb, I usually put it in "1" (eco mode). Once when I had a long climb into a big headwind, I put it in "2" (tour mode) and it was a big help. So far I have been riding just as hard (I was sweaty after today's ride) but I just go faster up the hills. Instead of working hard and going 6 mph up a hill, I now work hard but go 9 mph.
Today I rode up to Tucker Lake.

Direct links to a larger version of the images:
http://softtechdesign.com/images/corsa-side-view-small.jpg
http://softtechdesign.com/images/corsa-top-view-small.jpg
http://softtechdesign.com.../corsa-motor-small.jpg
http://softtechdesign.com...tucker-lake1-small.jpg

I just joined the board.  This is my first post.  
 
 
I went with the 750W Bafang BBS02 mid-drive on my 2009 Giro 20/20, but about 8 months later, I removed it.  
(that would be about three days ago). 
It was fun and all, but it made the bike way too heavy and, IMO, had a very negative effect on the handling, especially on high speed descents.  
 
The motor and cranks alone, placed 13lbs above and slightly forward of the front wheel, which acted like a huge, inverted pendulum, exaggerating or multiplying any lateral movement of the front wheel.  
At speeds above 35mph, coming down a long hill, even the slightest movement of my arms would send the bike jerking violently from side to side.  
That doesn't happen without the motor.  Sure, the bike is a little twitchy due to the smaller wheels, but the handling difference is night and day. 
 
For that reason, were I to reinstall the system, which I might someday, I would go with a hub motor on the rear wheel. 
That would keep the weigh low and to the rear, likely solving my handling issues.  
 
Removing the system resulted in the bike weighing half as much, which is nice if you have to flip it over to patch a flat tire, or carry it up a flight of stairs, like I do.  
 
For the anti-torque arm, I used the heavy duty version of the one noahvale used on his bike. 
https://california-ebike.com/shop/heavy-duty-bafang-stabilizer-bar-bsbhd-1/ 
 
Wanting the motor to be rock solid, I opted to drill a small hole straight through the frame to secure it in place.  
Worked like a charm!  
 
I used the TerraCycle battery tray, but I modified it so it would tuck under the frame, just in front of the rear tire.