Both the Hangar 9 and Sig caps are excellent aircraft. I prefer the Hangar 9 but opinions are like ...
The power loading with your 120 is going to be marginal. I fly a Moki 2.10 on mine, my buddy uses a 1.8 and I've seen them fly very well on the OS 1.6. I flew it for 1 season with a SuperTigre 2300 (1.4) and it flew well but only hovered on the very best days.
The Sig Cap is smaller than the Hangar 9 (950 square inches area and 73" span vs. 1100 sq. in. and 74" span) and runs about .75 lbs. lighter. You could pick up one of these and put it on a diet...
The Hangar 9 Edge is also a great flying plane and some have come in at 9.5 lbs. I flew one with a Saito 1.5 and thought that it was perfect.
However, Caps and Edges are about the worst scale design for precision flying. That is between the Giles, Edge, Laser, Staudacher, Extra, Zlin, Katana and Cap. If you want to fly precision get an Extra.