Well, they're only 6 gallons, which is really too small even for 5 gallon batches. Otherwise, it seems like they would do. I'd get two of the ones with spigots, myself.
But really, I'd recommend getting some kegs and converting them so you aren't restricted to 4 gallons or so. Or check ebay for cheap stainless kettles. The spring lids on those boxes won't be particularly helpful, though the spigot is a must.
Oh don't give me none more of that Old Janx Spirit
No, don't you give me none more of that Old Janx Spirit
For my head will fly, my tongue will lie, my eyes will fry and I may die
Won't you pour me one more of that sinful Old Janx Spirit