increased efficiency from no derailer
 

Is there much of an increase in efficiency from ditching a derailer and going to SS? i know it wouldnt be much, but im trying to figure out if its like 10% or 1%.

I'd say single digits is a safe bet.

Of course there is.

10%? Absolutely not that is hugely significant.

1% at best IMO.

Feels more efficient. Placebo effect, maybe.

But the feeling is real.

Studies have been done, and it's largely dependent on the amount of cross-chaining as well as tensioner drag and cog size. The best scenario is to run a front / rear combination with straight chainline, a large rear cog and a loose tensioner. Cheap derailleur tensioner pulleys with bushings instead of bearings can cause significant drag. That's why using a tensioner with a single speed setup largely negates the benefit of eliminating the derailleur.