Our roof is not very pitched so the attic space is rather short/tight. I haven't been physically up to see it myself due to pregnancy/recovering-from-pregnancy, but I am told that where the roof rafters meet the walls it comes down to a pinch point that is too low to allow access for spray foam insulation, since you have to get up pretty close to each section that gets insulated in order to spray it in.
I could have been more clear when I talked about future access. We have installed can lights, we are installing skylights, and have upgraded the electrical. We are also upgrading the HVAC ducting. Due to all of that we SHOULD have a low probability of needing to crawl up in the attic to do other work, but it seems like planning to never have to crawl around up there isn't the wisest decision. The general contractor's concern with the blown-in is that it will completely cover the joists and then some, so you won't know where to put a foot or hand when crawling around.
Has anyone heard of issues with blown in getting airborne due to an attic fan and then venting out the attic vents in the roof? To anser GuitarStv, yes, I mean a true ttic fan and not a bathroom fan venting into the attic. :)