Thanks for the additional beta, Yocum.
DPS - the guiding company is a US-based international guiding company. The actual guide has multiple first ascents in the Cascades to his name, as well as in the Waddingtons, Patagonia and Alaska. Of course, he is also extensively certified. I would be happy to share more specific details to those who are interested in joining me this June.
In regard to rock and icefall - yes this is a potential hazard. A cold snap (more likely in June than later in the season) would drastically reduce these hazards. I agree that this route should be less technical in June than it would be later in the season when the glacier is more broken up.
In regard to flexibility - As with any serious climb, safety and respect of the mountain (and particular route) are of upmost importance. As such, the guide and I are not locked into this particular route on those particular days. While it'd be great if everything if everything works out, if conditions are not favorable, we will climb elsewhere.
All this chitter-chatter is getting me excited!