Well Fant, Im not sure exactly about the Bandos or any armor for that matter, thats a mystery to me, but OT as far as the godswords here's my take:
AGS is the most usefull godsword and if you are going to use your protect one item prayer on your weapon, it might as well be the best for the situation.
BGS--drains defense, big whoop, this is basically a wannabe AGS and anyone willing to risk possibly getting a GS smited is probably going to be wealthy enough to go ahead and say F it, risk the AGS instead.
ZGS--no reason to waste your one protected item on something freezes when ancients already work so good, I would much rather have a 25% damage boost on my special attack and get 2 of them than to waste it on a barrage imbued into a GS, LOL
SGS--The amount that this spec heals/restores is hardly worth giving up a damage dealing special attack, as you will already be eating and using prayer pots to dodge all the smiting nooblets, a waste of a spec if you ask me to use this over anything that has a meaner more offensive special attack.
AGS--hard hitting, same max hit as claws but it delivers it in one big punch instead of HIT-smaller hit-tiny hit-tiny hit, and its spec is to just to hit even freaking harder, you cant lose with this one and If Im risking my AGS already (prot one item isnt as reliable as people believe), then Im going to go with the GS that has the most put-down power.
I'm not sure If this is the complete reasoning behind the odd price fluctuations since the announcement of the update, but its the best I can come up with being a GS pure, sorry I cant help with the armour, I would think the possibily of no skulling to keep 3 items (4 with prot 1 item), high level armor like this and dhoraks and stuff would be in high demand, but I guess there are other factors at play here that I am unfamiliar with.
Hope I helped, any1 else wanna take a crack at it?!?