Is there a downside of having too many features?
I'll jump in with an answer, though I agree with others that there is probably no single correct way.

My experience with features is that large features become very difficult to manage. Even one-feature-to-rule-all isn't a great answer, though it obviously reduces the conflicts possible, though that helps, because of the management of all those individual elements becomes hard.

In the past I have attempted to keep one "feature-module" for each aspect-feature of the site - so for example one feature describing a content type, and the views using it, and the rules, etc. Sometimes this is essentially one page, sometimes more. I have also tried larger groupings - bad idea - but not so far smaller ones (one for the actual CT, another for the view, etc.

The aspect of 'too many modules' is real, though I have dealt with perfectly functional sites with >200 (non-features) modules active. A mitigation you could use is for the live system to run with the features modules disabled, because their effect should be in the database and so the code is not needed. I haven't tried this, though.

From this experience I think that the choice should be to keep the scope of each feature small and very, very well defined. Most of the time I have got into trouble it has resulted from some aspect of a feature that is on the border between several elements -- it should probably have been its own thing not lumped into other things.

So: smaller features with very well defined scope for each.