Brett,
I had always intended to use a Harrison tank (in fact, I sourced mine Stateside years ago) so I haven't given much thought to the actual purpose of the two PACE tanks.
I have to admit, they do look like nice pieces of kit, but way too shiny for any of my potential purposes. I've been meaning to look in my manual to see 'why 2 tanks'? Covert onboard distillery, perhaps ?
I had thought I might actually use one as a windscreen washer reservoir.
I know you have used both, so what is the purpose of the second tank?
....and for those who might be thinking "what are PACE tanks" ....
Cheers!
Glen