Hello everyone,
Can you please share your experiences if you have travelled outside USA during Post Completion OPT?

 Personally I did not travel on OPT. But I know friend of mine who travelled to Nepal on OPT and ca,e back. He still had valid visa, plus he was working for a company here in US. Make sure before you travel you have  a job offer or have a job. Hope this helps. 

 Yes, it is totally safe to go back in OPT as long as you have visa, non expiring passport for next 6 months and a job offer.

How about job offer from consultancy but no client letter?

Too risky. Quite a few Nepalese have been sent back at POE/not issued visas in Nepal while traveling home while employed by Indian consultancies. 

I heard of this dude that got sent back from his POE (Chicago) for failing to provide employement verification posted on his 'resume'. 

Hi,
Tarveling in opt could be risky, if ur job is not e-verify or its not related in your field. Make sure you must have a non expiring passport for next 6 months. But, its depends upon your POE.
Best of luck.