I installed your component today and it is really nice, thank you!
I did find a little problem with the captcha image URL, please note the double forward slashes (//) after the domain name.
http://www.mysite.com//components/com_comment/joscomment/captcha.php?refid=a4e63deb3e895bb01cc0c1fdf8f97e06
I have Joomla's default SEF turned on (with mod rewrite) and this caused a problem on my site. Basically the captcha would not appear.
My URL rewrite does not rewrite anything in the /components folder. I had to modify my rewrite to include //components and then the captcha appeared!
Anyway, just thought I'd post this in case others have experienced similar issues due to the double forward slashes.
Thank you