wallstein,
if i may, a couple of things, 1) thanks for putting in the effort to replace what needed replacing.
2) when the route was put up, the bolters were using what was, at the time and of course, within reason, the best tools for the job. 1/4 inchers were the standard. they didnt take that long to drill and its what climbers of that era were using. im sure they werent laughing with each other at the thought of these bolts breaking or pulling out, sometimes under body weight, on the generation of climbers to follow. if they had bosch's, and the ability to see the future, 3/8 might have been the choice.
the point is that they didnt take it upon themselves to contrive some mix of metal so that THEY could give following climbers something to be afraid of as they clip a chunk of metal. the exciting part isnt supposed to be the bolt ladder. dont take it upon yourself to modify or affect the fear factor of an existing climb (especially a classic) so that it can seem like its 1966. none of the other gear you use or slings replaced on most climbs from year to year is from 1966, why the bolts?
its 2001, not 1966 and bolting responsibly should mean that if your going to put a bolt with a hanger in the rock, put in a good one. you'll make more friends doing that than tying up the belays pounding metal for weeks on one of our classics, all the while thinking way too much about what you want everybody else's climbing experience to be.
there is a bolt ladder there to span a section of rock, and your not going to turn an A2 into an A1 by putting good bolts in the A1 bolt ladder. im glad your replacing the mank up there with what you should have the first time (and not 1/4 in x 3/8 dowlels or something). plus it offers the option of free climbing without someone changing it further.
those bolts broke because 1/4 inchers suck, regardless of who OK'd them.
if you need a bolts or hangers or a partner with a drill, ill donate.