Same size, that helps!
Err. No. The Fluval tubes that I am using are as supplied with the 406, not conventional filter tubing but the ribbed stuff. They are a good but looser fit than the Ehiem tubing as provided by Ehiem. Using the tube clip as provided by Ehiem I am unable to pull them off.
I am not sure that I should recommend this as a course of action as yet as it is early days and problems may still develop.
From one of your earlier posts I see that you do not use the Fluval tubing as it "reduces flow by design". (I feel you my be right).
I would double check your hose sizes if this is likely to cause you an issue.