Adam....first off, regarding the rubber seals on the hose. Yes, the E Series does NOT swivel, so putting a rubber seal on it would make sense, since it wouldn't get damaged over time with usage. Also, the E Series was the first model Rainbow introduced to have their 'Hepa Neutralizer' & be certified as a room air cleaner. Perhaps the rubber seals were put onto the hose end to ensure no possible microscopic leakage of dust around the hose opening on the canister?? Just a thought there....
Now, regarding the power nozzle & sealing to the carpet....You have the Performance Edition PN with the belt in the middle, right? If so, that PN, as well as the E Series PN that came after it that just added height adjustment, the belt being right in the middle causes the airflow duct which airflow moves & dirt carried away to be smaller/slimmer than normal....therefore chokes off some of the airflow the canister could deliver to the PN. And after all, this is a PN that many Vacuumlanders have complained about airflow not being the greatest, & considered a design flaw. Perhaps you should try finding another PN to use....such as a Eureka Express w/VG III?
Rob