Yes.. that was always my point when the discussion went toward the new licencing. I think that everybody understands that they got to pay something when they are able to do some work on a cheap hardware bought in a supermarket. But to have to pay for accessing with a iOS device that comes from the 'same' company and costs easily three times as much as a cheap PC??
But it seems that I'm alone with that point.
Of course, FileMaker gives the GO app for free - and IMHO that's the point that one has to pay for iOS-access as well
If You got 10 connections from Your hoster, WD and iOS clients can access - up to 10 at the same time. It's not a 'IWP' thing, it's more the difference between Server13 and Server12 (or older). Using IWP for iPhones is not that cool (web-layouts)...
When it comes to pure web-access, You have to compare the cost of WD with the old Server Advanced, that's not so bad. But the iOS-access...
On the other hand, I did some comparisons for customers, comparing WD and IWP. I did not test the app in daily use - but I did test the time one needs for updating the FM database, rewriting... and there, WD is much faster. Sure, You have to deal with some disadvantages - but I felt much better on WD - and the solutions were easier and really faster to produce/maintain. Even overworking an existing IWP solution to WD was done in a very short time (of course, depends on the solution and other factors..)
(edited, clued two answers into one)