I must make a difficult decision, so am having to turn to the wider community to gain some perspective.
My situation is the following: I am currently outside USA and am trying to enter academia here. I have been invited as a visiting lecturer at a top US university. However, I am worried that though certainly valuable, a purely teaching position might be a huge negative against me in terms of prospects for a more research oriented position (Asst or Assoc Prof). Or is my trepidation unjustified?
The title of lecturer does not necessarily imply that you would teach full time. Sure, it usually implies more teaching than research, but that does not mean it's strictly teaching only. Especially for a visiting lecturer position, one could imagine there be arrangements possible.
So: have you checked the exact term under which you would be employed?
Also: how long would be this “brief” position? And what is your current seniority in your local research system? Those factors will play heavily into the decision.
Overall, I expect it's a net positive for you if you manage to keep some research activity going on, especially if you can travel relatively often to visit your non-US lab. Otherwise, if it's purely teaching with no opportunity to maintain some research activity, and you are not far from getting a job where you are, accepting might be risky.
“Long absent, soon forgotten”