[SlaterSpeed]

The o-ring should be fine

If you need to use a filter with the cascade and not with the whitewater then whats the point in buying the cascade in the first place as surely the filter will cause a bigger loss in performance than will be gained by the better block design.

Filters are all well and good aslong as they are not restrictive but i cant relly see an inline filter having low enough resistance not to cause problems.