Grant,
I'm of similar belief as you. They are old guns. They are not particularly well made, in today's standards, especially a field model. The graded guns got more attention as the grades went up, I'm guessing from the quality of fit and finish.

But, if a guy wants to shoot high volume targets today, a modern target gun is what I'd use. Not to say I haven't taken a Fox out for a few weeks in a row at the range, just that I haven't done it year in and year out. However, I am suspicious we have some here that have done exactly that. Possibly, guys like Mike Campbell and others shoot these old guns a lot. I'd be educational to hear their perspective.