Thanks for the input, both of 'ya.
The basic premise that I worked off of was trying to find a safe number that I could add to each of the id's that would work for both databases. There was a lot of room for optimization, which I've incorporated below (and updated the web page that shows what I do for each table
here):
npc_types.id: increment by 350,000 rather than 500,000
spawngroup.id: increment by 300,000 rather than 3,000,000
spawn2.id: incremebt by 125,000 rather than 500,000
npc_spells.id: increment by 300 rather than 5,000
npc_spells_entries.id: increment by 1,800 rather than 5,000
loottable.id: increment by 13,000 rather than 500,000
lootdrop.id: increment by 50,000 rather than 500,000
faction_list.id: increment by 1,000 rather than 5,000
items.id: increment by 100,000 rather than 500,000
As to the "will it work" thing, I've been doing some pretty extensive testing and its all worked so far. Thanks for the input.