What eye piece are you using on the 664 ? I found a 773 angled at a good price but still $2000.00 with eye piece vs $1280 for a 664 . I feel the straight would be better also. Also 554 for 1632.00. How does the 554 compare to the 664 ?
I probably will use mine for both, won't be thanking any pictures with them. I have a pair of Leitz bios a Leica made from the 1980's and just about as good as the SLC's but color probably better with Leitz.