If I only consider within Oly I would say yes the ISO is a welcome upgrade......... now if I add other brands.... its a different ball game.... There are some entry level cam that cost half of E5 that could perform similar or close to it.....
I dont think anyone from other brands will migrate to E5... still find E5 a bit 1 or 2 yrs behind its competitors...
Sorry guys this is just my observation...
Well, that is true, but of course, one doesn't look at one aspect and then go "OH! I'll get this cause its good!" so there will be others, I've heard stories that guys from other brands move to Olympus because of the anti dust, probably a few other reason but that's what I heard, if you do lots of studio work, don't think you would need high ISO performance now would we? Of course that is just one thing, maybe I do lots of flash outdoors? Then I wouldn't need high ISO performance, but rather I'd want the Zuiko quality and sell off my current gear for Olympus.
Whatever reason, all cameras today are more or less competent tools but its individual preferences. If they do not want to move, that's their decision, most important is your personal decision, aye?