I think crampoons and a light weight ice axe would be prudent at this time of year judging by the pic in the recent Bugaboo tr. I have been there in mid September with ok weather. Of course the trip ended when it snowed a heap.
That weather link is a good resource to follow. Also, if you check out the 'chick on ice' TR you can get a sense of how much the cols are changing. If you're still thinking about the East Creek, weather may play a pretty huge role in success or failure. Something for nothing, I got word last week from some folks up at Applebee and it sounds like folks are wrapping up their projects for the season and heading on to other climes.
east face of Snow patch, cresent spires etc would be fine, if a little chilly when the sun leaves the face. Not much inclined ice and bergshrunds for those routes, but everything else you better have poons and ice axe.
I was there two weeks ago.
It was iffy when using the B-S col. Rock falls on the right side are a big concern. There is a fixed rope to help you negotiate the climb up the col once you are over the crevasse/bergschrund (as of August 27). People are inclined to use the Pigeon-Snowpatch rappel route on the way down instead. Crescent spire and towers are good options to avoid afternoon rain/snow.
Have a good time and be safe. There was a fatal accident involving a father-daughter team before I got there. The father was the victim. Very sad situation.