Would there be any issues I should be concerned about if I were to to run my a/v cables and speaker wire through the same 8" x 10" perimeter soffit I am putting 4" recessed lights in?

I can try to keep the smurf tube in the upper corners of the soffit. This would save me a ton of stud drilling. Maybe i can even make a small "soffit within a soffit" to keep the A/V wires where they are.

Any ideas?

No problem. Try to keep some seperation between A/V and power running to your can lights, and cross at right angles where possible.

I also have data & speaker running in my soffits.