We use BD 6808's other then the last year, we have had no problems with them. This last year we have had a number of RMA's, which stemmed to a product manufacturer they used. They are replacing some blades, as a prevenative measure, to bring them up to the current revision.
Tech support: Line 1, typical, some are good, some not so good. Line 2 preety good. We have never really had a problem there.
documentation I would say is there biggest weakness, there have been features that I tried to look into and all they have is a 2 sentence paragraph on it.
Software: the last year they have added alot of features, and there have been some bugs, they are quick on finding them and getting a hotfix out. Rule of thumb: test before you upgrade.
Overall I would still go with Extreme.