Jim,
Here is another thought for you as you are probably not familiar with a fully modular medium format camera. No need to carry a seperate 35mm camera if you get one of these. Bronica probably sold more 35mm film backs for the ETRS than the SQ so they do turn up from time to time. The SQ variant is a lot rarer. So then you can swap between 35mm and 6 x 4.5 at will.
Link to the ETRS item on e-bay so you can see what one looks like.
http://cgi.ebay.co.uk/Bronica-135W-F...item45ef4987ce
Don