I have the 73" Yak with OS 1.60. I had the OS 1.20 for the first 6 gallons I got around 9.5 min on a 16 oz tank and land with 1/8 tank reserve. Now with the 1.60 after 1.5 gallon breaking in, I fly 8 1/2 min and have over 1/2 tank remaining because I can use better throttle management with the bigger engine. most flying is at half throttle or less with plenty of power for vertical stuff.

BTW the 1.20 had everything as far forward as possible for balance, but it did balance ok. I made lots of mods when I added the 1.60 and the weight is now 11 lbs. with the 1,20 the weight was 10 lbs.

my feeling is the 1.60 is a better choice all around. I love every thing about this motor. After 1/2 gallon I added the perry pump and moved the tank back to the tube. Still playing with battery position to get perfect CG for my style. Battery is just forward of the rudder servo location, however I moved the rudder servo to just above the right elevator servo with short rod and ball link.
I added Seagull Ultimate Biplane landing gear +3 oz weight over stock but sooo much better in every way.

APC 18 X 6 W = 8450 RPM
Slimline large volume pitts style muffler
Perry pump
Cool Power 10%

This is a great combination but I dont like the APC I think it comes up to RPM to slow, I will play with props in the spring after more break in. Any suggestion???
Hope this helps
Ron