I trust you have seen the reviews on here:
https://electricbikereview.com/add-e/250w-kit/
https://electricbikereview.com/add-e/600w-kit/
There are also questions with any friction drive as to how long the drive's surface will last, and also how long the tire being driven will last. Also there are questions about the traction the drive system will have in less than ideal circumstances, i.e. wet or dusty conditions.
I have pre-ordered another competing friction drive called the ShareRoller. I wish I could tell you how that is working out, but the initial shipments have been delayed (they are now saying mid-March for the first shipments). Court reviewed an earlier version (V1), but since then they have made major revisions and are now up to V4. Here is Court's review of V1:
https://electricbikereview.com/?s=ShareRoller
You can read more about it, including updated features, on the forum here:
https://electricbikereview.com/foru...y-described-illustrated-here.3176/#post-88097
One possibly helpful piece of info is that V4 will have a means of attaching it to the seatpost for use on the rear wheel. If you are concerned about using a motor on carbon fiber forks as in your other post, that might be an option if you happen to have a steel seatpost. In general, it is usually not a good idea to clamp anything onto carbon fiber tubing.