My Samsung BluRay player used to re-buffer constantly, even though it was detecting a good signal strength. After spending hours trying to improve radio connection to my wireless router, I spent twenty minutes and twenty bucks running a Cat 5 e cable to hard connect it and the problem was solved. If Roku has a better receiver or a better error handling system then it may solve your problem...or not. 

slartabartfast
My Samsung BluRay player used to re-buffer constantly, even though it was detecting a good signal strength. After spending hours trying to improve radio connection to my wireless router, I spent twenty minutes and twenty bucks running a Cat 5 e cable to hard connect it and the problem was solved. If Roku has a better receiver or a better error handling system then it may solve your problem...or not. 

My Samsung SMART BR Player was a re-buffering POS.  Hardwired CAT5e.  I connected the Roku to the same cable the BR Player had been using and I've had nothing but streaming joy since.
 
This is on and internet pipe with 3.5M down and 750K up.
 
IMO, the Roku must have a deeper buffer and better fill algos.  I'm a 100% happy Roku camper.

I also have a Samsung Smart BR player and that's what I've been using lately and I'm connected wirelessly.  so far I've not seen a buffering problem.  but I do have 23Mbps download speed, so that probably has a lot to do with it.