I did phone humber re the bungs and was passed from sales to someone in the manufacturing team, which was reassuring, and yes they suggest we leave both bungs out as inevitably as all have said on here, water will get in one way or another. Hatch seals or bungs expanding and contracting. It's best being drained than stagnant and filling up.
By leaving it open they said it drains and lets air through, rather than water building up. The only downside being it would sit lower in the water if one of two things happen. 1. You stuff the boat 2. Your bilge/transom well pump fails and the boat floods. Either way, the difference would be negligible.
I didn't post the pics on the under deck layout, but I recall too there were some posted. There are two ridges/struts (??) that run the length of the boat a 1/3 of the way in from each side to support the deck and provide a channel from bow to stern, that drains water from the bow locker to the transom well.
I'm still confident in Humber considering their instructions and responses to me. There are thousands of hulls out there that are solid and ours after 5 yrs seems solid too.
The Original poster Nugent's boat seems a bit if a mess. He subsequently stated it had undergone a poor fit out and suspected that did not help.
He also stated that he had to be careful with his words, due to a phone call. I'm still v curious as to what this was about and from whom? He hasn't posted much since. I think considering the inference on Humber build quality, whether intended or not, he ought to follow up....
It came the day after I asked them for clarification on build process. Coincidence? I don't know.
Hi res Anglesey pics
Alex Whittaker / Shedpix Donations for Round Anglesey Macmillan 2014 https://www.justgiving.com/Rib-net