"You can, however, access Bell Fibe TV content on Roku through other supported devices like Apple TV, Chromecast, or Amazon Fire TV" This is not correct. You can replace the Roku with these other devices, but they won't allow you to access Fibe TV on...
The Fibe App IS very, very good. I would give Bell some time first and try it out for awhile. The DVR functionality and availability of you stuff via the app is great. You just have to live without series set up and onDemand content.
You can't FF anything that you "restart" or that is OnDemand (even if you rewind it). I don't use the Record Series feature what so ever, it's a pain and very unreliable. For sports I record what I want on a day to day basis. e.g. tennis gran slam ...