Hara does like his white springs
One way to keep the competition guessing? Paint your springs.
About the diff updates - be glad that HPI is committed to updating the cars as necessary. Someone mentioned that Tamiya still has problems with their Evo 3 which is strange knowing Tamiya. Stuff is on the way, so don't worry about it too much. If you're still on the fence and haven't gotten the Pro 4 yet but still want to, try to wait another month or two, the bugs will have been worked out by then. Minor handfitting and things like soaking the gears are kind of the norm with a brand new competition-level RC car.