RE: servo size and torque???
A .15 on that size plane should perform like your name: Speedy -- unless it is very heavy.
If 12 in-oz. is the actual rated torque for your servos, I would recommend choosing another. The Hitec HS-55 is rated at 15 in-oz at 4.8 v, and while many on this forum are using the HS-55 for control surfaces, others are using the larger HS-81 (36 in-oz) on planes in the 32" to 36" range. One of the problems with the mini/micro servos is not necessarily associated with the servos capacity to generate rated torque figures as much as the ability of the gear train to sustain continued loads without shearing teeth. Also, many of us are flying models approaching the size of your plane with engines of about 1/3 the displacement. The servo choice most of us make is mostly dictated by weight and size -- a savings of 2 ounces may represent 10 to 15% of our models weight.
Unless weight and/or servo size is a real consideration, I think I would use the HS-311 standard for surfaces and an HS-81 on throttle.
There is a lot of experience on this forum -- read the posts, absorb the information and make your decision.
One thing I always try to keep in mind is "Just because it's my opinion doesn't necessarily mean I'm right!!"
the "other" andrew