Infusions are an upgrade ?
I dont know much about the SAB, but when it comes to infusions…why dont you just extract it beforehand to be sure?
The extractor is cheap enough and its better to take no risks at all.
Infusions are lost when upgrading ascended items in the Mystic Forge, since the original item is consumed in the crafting process. Make sure to use an Infusion Extraction Device before you do so.
(gw2wiki)