Perhaps there is a little over analysis here.
You have a 10hl system with 10hl wrote on the box, the revenue boys looks for the 'agreed' bond based around that setup - it sounds like these bonds might be a little flexible - after all its not in their interests to shut you down.
With regards to output - they will see your output as time goes on either way - so fudging that number doesnt make sense.
My question was with regards to these brewing systems advertised, so I take it a 10 hl brewing system is designed to produce a 10 hl, tweaking OG down could increase volume and tweaking OG up will probably reduce volumes.
I have to visit some of these irish micro-breweries soon.
James