Well I'm assuming you've eliminated EVERY other variable, and actually tried to tune them? Did you just shoot them, or did you try to tune them to the bow after you got the "poor" tear?

I had a Legacy with the 28.5 " cam...3-60's were too stiff in my case, and CX 300's were borderline too stiff...I ended up shooting 3-49's in it ,and they flew like bullets...

To see if spine is the case you could do a couple of things w/ the 3-60's....

1) try shooting 125 grain tips to weaken spine..
2) lighten spring tension
3) Use feathers on the back to weaken spine
4) use a combination of the above

I shot 3-60's out of my Q2 at 76 Lbs with 125 grain points and vanes and they were still a bit stiff..but they shot well, and I don't pay too much attention to slightly off tears...I'm ot perfect and I make mistakes...In addition I like a slight high left tear (for a righty) to give the arrow some "direction" and keep it from knuckleballing.

A nocking loop will generally require a softer spined arrow than releasing directly off the string. Up to 70 Lbs on most bows with an arrow in the 27 to 29" range a 3-49 will do most of the time...especially with a loop, and vanes on the back end of em.