Pulling filament through long tubes
I would say it's not the best approach. 

In the situation you've described I would rather install some kind of vertical ring a bit above your printer. This ring would organize your filament going from any direction. 

So let's assume you got one spool on the right and one on the left of your printer, both are 1m away from the printer itself. If you get filament and put throught the ring then to your extruder.

In my opinion the ring should be around 15..20cm over the printer, it should have around 10..15cm diameter and spools should not be too low.

The only issue I see is unwinding spools which are too far from the printer because then filament would be unwinded angular but the same issue would be with and without teflon tube.

[edit]
Here is a simple change of your design



[edit2]
Please also note that you can assure proper angle of unwinding filament by installing small rings ("eyes") next to spools. These eyes will direct filament out of spool and then filament will turn to your big ring mounted on the printer. This is common solution in textile industry