Sorry, slow, just saw this.
The key issue I think BS ignores is late kettle utilisation, specifically the whirlpool. I used to work with a IBD Bass trained diploma master trained brewer and he ignored it as well, being used to low AA hops in the 80's saw him miss the issues with high AA new world hops. With the raft of new high alpha flavour hops (topaz/galaxy as Aussie examples) the contribution of AA at whirlpool is significant, per below.
Thanks to the photospectometer, I can show I am getting upwards of 30% BU contribution at the whirlpool on the calculated bitterness. (using a new 15bbl DME steam heated system with 40 minute run off). ie., in a USA Pale using Citra/Cascade in the whirlpool I am getting 10-15 BU from the whirlpool (target 40) and have had to dial back the bittering hops to 25 BU to compensate.
On a lighter golden ale using topaz is event worse, with a target of 20-25 BU, I aim for 6 BU at bittering and am getting upwards of 30 BU from the whirlpool. So, I am taking out the whirlpool fraction and adding to the dry hop. One batch saw 35 BU come thru from the whirlpool hops.
The net affect would also be an issue for HB'ers cooling wort in a cube. I have no doubt most aim for the target BU from the initial addition, neglecting to wind down die to the excess stand and exposure times.
So, i dont know if the utilisation needs to go to 200, perhaps more the late hops need to be accounted for rather than showing 0 for BU contribution.
I dunno if and when I will revisit this forum (away for next 6 weeks), ping me an email at scotty@rocksbrewing.com as a follow-up and if I am getting the setting wrong.
Apart from that, I find the efficiency accurate. The new brewery claimed they had 90 efficiency, I claimed 72. Thier auger broke down, had to mash in manually and had thier efficiency jump near 15%. The auger was also churning the grain, whilst the head brewer was increasing mill gap to try and compensate and I was commenting on how fine the malt was. They should have listened to the BS calc's as they were spot on!
Scotty