Sorry, you are correct with the overall OS function but regardless of the OS it would say it is a downgrade in feature sets....true that Playbook OS is a completely different OS but its final feature set and capabilities are OS neutral and the fact is the multi-tasking capabilities of the Playbook seem to beat the multi-tasking capabilities of BB10 at the moment. I have both Q10 and playbook and use the q10 more often simply cause of form factor and physical keyboard (had a Z10, then went to 9900 cause of better bridge functions, and then went back to BB10 with q10) and I hope blackberry tackle these issues or allow users the same type of options.
I completely understand its not a huge demand for this capability (from what people have said iOS and Android can't do it) but in terms of creating a richer more robust OS then Blackberry obviously know how to do it (i.e. executed amazingly well on Playbook with its multitasking) but it's perplexing why those same ideas and workflows weren't translated onto a far more capable and efficient hardware in the BB10 phones.