I saw Adam Pawlus called the R5-M4 droid "just different enough to make you mad", but I gotta say that's way off the mark... This droid is pretty significantly different. The orange isn't even the same shade/tone as the orange on any of the BAD parts. It's got all the very noticeable silver highlights (which I mistook for white in the pics before I owned it), and almost every panel/detail is painted differently in one way or another.
Gotta say this doesn't fit the bill on that one for me. You can't build this droid at the park, at all, or come even close to it really.
Agreed - unless he's referring to the fact that you can (or could) have built an all-black R5 droid at Disney in the past, then, yeah sure, it's "different" - but to me, the second the color changes on a part that makes it different enough to make me want to add it to my collection.
There is only ONE droid combo where he "just different enough to make you mad" might apply and that is the white w/yellow R6. In wave 1 (2012) it was a orange-yellow color and then when wave 2.5 came out with TFA droids, it was more of a lemon-yellow to go with the white w/lemon-yellow parts from wave 2 (2015) - sure some of the panels were painted differently and there was more silver in the wave 2 trunk, but yeah - those are two fairly "close" droids, but if you're going for all of the versions of the parts, you HAVE to include them.
At the end of the day, the Build-a-Droids at Disney are so varied, it really does come down to collect what you want - if you want all of the parts go for it, if you want 2x of each dome on two different body designs, go for it, if you want just a handful of droids made up from your favorite colors, go for it and if you want none of them at all, that's an option too, they aren't technically "Hasbro" so you can play the "Hasbro purist" card and skip them altogether.