Last I tried a loop, I used a simple wire loop of about 10 cm diameter
(for a 1 m antenna diameter).

The coax version might save you some noise when receiving, but I never
tried coax myself, I use solid tubes.
For transmitting, coax or not should make no difference.

I do have an antenna tuner for the plain dipol. For the loop, you never
use antenna tuner.

For tuning the loop for transmitting, I find it easy to make the
coupling loop variable in size, and just try smaller/large loops, and
then fix the size when satisfied

Christen
oz1aab