I re read this thread.. again..
I understand the concerns and it's fair to say that using the Smartwater bottle to back flush is not a once size fits all solution. Where I hike, most of the water I drink doesn't need to be filtered in the first place but I do as an extra margin of safety. It's very clear with no visible algae.
For what I do, I can back flush the filter in the field with the Smartbottle and then hit it with the syringe before I store it after the hike. If I'm wrong, I suspect the worst I'll see is a slower flow rate. Even if the filter completely failed, I carry purification tablets for that contingency. If this was a $200 filter I'd probably be more anal but at $25.... meh!