Ha! I borrowed surgery suture from my wife to stitch that netting on my Fastpack 350. And, of course, if you have the tripod on that one side, there is not room for water.
Congrats! Especially with the 50% off. I am sure you'll still like it. I did look at the Whistlers. As you just described, they have a lot of good features and seemed to be great bags. Its funny you mention V1 vs V2 having and not having an ICU. If I recall correctly, that is why I stopped looking at the Whistler, that I wanted an ICU system. Looking at Lowepro's website, it does look like V2 you can remove the camera insert, but I do not see other smaller ICUs that would be interchangeable ...just the one that comes with the bag.
Anyway, looks like a great bag, hope you enjoy!