I got a KONIFLEX (type I) in early 2012. It IS rare. In late 2011 I searched the entire eBay ,Taobao and Yahoo! Taiwan/HK/Japan for months but could not find even one listed for sale. Finally I got one from Yahoo! Auction Japan. The condition is Ok. Not too expensive (30,000 YEN), but very difficult to find.
One of the ways to realize the rareness of KONIFLEX is to search it on Flickr. If you pay attention to the search result you'll find:
1. There are only about 300 images totally.
2. These 300+ images are uploaded by about only 5 users.
3. Among these 5+ users there is only one who is still actively using it, contributing 80% of the 300+ images (that's me
😀)
I've read somewhere on the web that one of the reasons Konica has produced and sold only a small amount of Koniflex is the price tag. It's priced unusually high in its age.
It's my first and currently only TLR so sorry I can not give you advice on how it compares to Yashica Mat. But if you ask me if I like this camera, the answer is: Definitely!
To me the quality of the Hexanon lens is good. I only use a conservative "good" instead of "excellent" or "extremely good" because sometimes I feel there is a degrade of image quality on the edges of the image, especially when the edge is out of the depth of field. I could not describe it precisely but if you are interested, these are some examples (notice the edge of the images):
http://www.flickr.com/photos/marinne-_-/9655947118/sizes/l/in/photostream/
http://www.flickr.com/photos/marinne-_-/8305675721/sizes/l/in/photostream/
Not sure if it's only my Koniflex that has this issue or all other Koniflex also have it. But overall I'm still satisfied with the image quality. Mostly the images are very sharp.
(To those who want to own a KONIFLEX: Forget about eBay. Right now there are 3 items for sale on Yahoo! Auction Japan!
Check it out)