First thing would be to ask yourself what part of Cisco's DNA and SD-Wan services are you specifically looking for Since DNA is a Cisco branded product. SD Wan is more universal and there are many offering SD WAN hardware. To my understanding Extreme does not have a SD WAN offering at this time and as for as DNA they have some centralized system control ability through some open source produces and then there is their Fabric offerings...
I would find a good sales rep and ask them this same question or post your list of options and needs that you feel Cisco DNA will handle so some of us may be able to answer you..
