My experience tell me:

* The Company name/brand can do as much to typecast you as the position. Eg, Dave's Zert Manufacturing vs Trendy Bay Co

* 'Instructor' can simply be a high-end gradient of many different roles. It doesn't necessarily say 'non-coder'. A senior architect can be understood to be an instructor of sorts. How this is all documented on a resume is fairly flexible.

* Academic teaching time would definitely typecast you negatively as a programmer, but not so much with System Administration experience. I'd avoid it unless you are headed into Academia. I don't have any very specific examples of this other than the perception I had of various co-workers who had come from university jobs. They had detectable institutionalization.

My general advice would be to have a clear picture of where you want to end up and do your best to have each link in the chain moving you in the same direction. It's easy to justify getting sidetracked by relationships, geography, and economic considerations.

I'll end with a useless caveat about subjective answers. Everything obviously depends on the specifics of the company and job.