The problem with WebSockets is that hey are: 1) More complex and binary so you cannot debug them as easily, specially on live and specially if you use HTTPS.

The problem with WebSockets is that hey are: 1) More complex and binary so you cannot debug them as easily, specially on live and specially if you use HTTPS. 2) The implementations don't parallelize the processing, with Comet-Stream + SSE you just need to find a application server that has concurrency and you are set to scale on the entire machines cores. 3) WebSockets still have more problems with Firewalls.