I wish someone with one of those could post a motherboard's photo + syscheck
That you want to see a SysCheck pretty much confirms you wouldn't know what you were looking at in a motherboard photo.
EVERY IOS that is in the latest official update will be there. They all need to be there or certain games/channels won't work. There won't be any exclusive IOS, because that would only be needed if there was exclusive software. The only possible difference is the lack of MIOS (dunno if it's there or not, there is no reason for it to be, but assuming they have not modified System Menu at all, which I guess they haven't, it'd be installed by WiFi and disc updates anyway, so they may as well put it on, so that discs don't prompt for an update, just to install MIOS).
Maybe they have an updated boot1 or boot2, but there would be zero point in that seeing as there is nothing wrong with the old ones. Nintendo aren't going to waste time making software changes here, all they're trying to do is cut costs - wasting time modifying software that already works isn't a good cost cutting move.
Even hardware changes are probably minimal. They'll have cut down the costs somewhat, but the hardware will need to be similar so that it will still be compatible with the same software. They've obviously cut out some hardware like GC controller ports and memory card slots, as well as perhaps some other GC mode related hardware. And they are probably using newer, cheaper revisions of other pieces of hardware (not the first time this has happened for Wii, there were new revisions of the processors at various points before, most notably the "LU64+" wii's, where the new processors were incompatible with old IOS). But there will most likely be nothing of extreme interest to be seen inside the revised Wii. Certainly nothing useful that will benefit the homebrew scene in anyway, all it would achieve is satisfying people's curiosity.