REAL LIFE EXPERIENCE HERE
I used one all the time with my Zenza Bronica Sq-Ai for exactly the same reason: shooting portraits with the standard 80mm lens.
I also used to add cheap close up filters from Ebay for a tighter crop on the model's face.
According to everyone I should have got horrendous results because of the rubbish quality of the Chinese close up filters plus the addition of the teleconverter. I really couldn't see any problems in my prints, probably my eye isn't trained properly or the problem isn't really that evident in portraits.
I personally couldn't give two hoots about lines for millimetre and the teleconverter was cheaper and lighter than a longer dedicated lens.
If weight and portability are an issue for you, I'd say to go for it.
I used one all the time with my Zenza Bronica Sq-Ai for exactly the same reason: shooting portraits with the standard 80mm lens.
I also used to add cheap close up filters from Ebay for a tighter crop on the model's face.
According to everyone I should have got horrendous results because of the rubbish quality of the Chinese close up filters plus the addition of the teleconverter. I really couldn't see any problems in my prints, probably my eye isn't trained properly or the problem isn't really that evident in portraits.
I personally couldn't give two hoots about lines for millimetre and the teleconverter was cheaper and lighter than a longer dedicated lens.
If weight and portability are an issue for you, I'd say to go for it.

