I've had a v1 for 18 months, no problem at all.
The thickness of the KappaSphere version (if that's what you're looking at in terms of a removable) is well within the allowance of the rubber gasket. In fact, I think it is about as thick as the multi-layer top when it passes through the same space...
So, you could argue, if you have the top up you may displace the seal somewhat... Placing the plastic sheild in that space with the top down "seals that gap" and keeps the spacing there consistent.
It takes no more effort to close the trunk with the windscreen in place - no more than it would if the top was up.
