My friends and I climbed the Mountaineers Route at the end of September last year. The weather was great, plenty of water and sunshine. This year there is LITTLE snowfall which I think will make the whole season a great time.. Soon after we climbed the mtn storms came it and it seemed that is the case with most years. Mid Sept I think is your best bet and I would not make it much later.
A friend and I are going to climb the MR again at the end of April and will keep you posted as I know its hard for good info to come by sometimes when planning.
We encountered snow/ice at the "notch" but I doubt this will apply to you if your coming up and intersecting the main trail on the ridge. happy climbing
