Having recently swapped my Eheim 2080 for a JBL 1500 I decided to try a few different configurations for intakes and outlets to see what sort of different glassware makes.
I wont bore everyone with the details, but basically the type of intake seemed to make little difference to the amount of water the filter was pumping. I didnt do any timed measurements into a bucket but the flow out of the outlet seemed exactly the same with either a glass intake or plastic intake.
What did make a difference was the type of outlet used. Now this I dont think actually changed the amount of water being pumped by the filter, what it did do was change the flow around the tank. The glass 'lily' created noticeably less flow around the tank compared to a plastic eheim 'crook' (NB - I didnt use the spray bar just to the 'hook' with no attachment). This I am thinking is a result of the wide lily mouth that allows the water to slow down quickly upon leaving the lily, whilst the plastic 'crook' keeps the flow in a concentrate 'flow' and thereby increases the force with which the water if pushed around in the tank.
Given this I'm going to use a glass intake and plastic outlet from now on. For me it is the plastic intake that looks the most ugly anyway.
Sam
PS - I also had a glass lily break on me the other day. Luckily enough I was standing next to the tank at the time so I was able to grad it a put it into the tank, if I hadn't been it would have emptied half the tank on to the sitting room carpet. I think the lily was sucking in air as it was close to the waters surface and this was causing it to flex which eventually snapped the 'lily' part clean off!