Hey guys. Sorry about being inactive for so long!
Had tonnes of work and loads of new clients
Anyway, now I can finally get back to finishing this off!!!
Auere, while I agree with most of your points.
The Firebelly, yes I agree it is a VERY strong choice in "most" match-ups, however the Butcher is also very powerful with the right combination of lores and units. The reason they will both remain ranked the same is because neither is more powerful than the other 100% of the time. They are both situational models and points dependent. Butcher offers more flexibility in the army, while the Firebelly offers only the "fire" lore and costing a little bit more. The 4+ ward against flaming attacks is negligible as you can get a 10pt item for 2+. I will leave the rankings the same, but I may re-word some of the entries in the future
Ironguts + Bulls are very strong choices for core, some of the best in WHFB!

However they are victims of their own success! They are tough, hard hitting and well... tough lol. However they have a very low weapon skill and Initiative, If they were say WS4 or I3 then they would be an A easily. As tough as they are they have a few weaknesses that are fairly easily exploited, that is the reason I have left them at B and B+. Again like the Butcher/FB comment they are situational units, both brining their own strengths and weaknesses. The Ironguts bring strength and a hefty point cost, the Bulls bring pretty much the same, just a little less of each

Compare these to most core units out there they would easily be an A, but against the rest of the ogre book I have bumped them down to a B so as not to show clear "favouritism" of one over the other. The choice is for the reader to decide, If I marked them A + B then it would make one look a lot more favourable than the other and this is what I want to avoid. The units are situational and ogres work better than IG's in some match ups and vice versa. They are situation dependant and up to the reader to decide
Maw seeker, I almost agree with your comment

The 40pt price tag is costly, however the Stupidity is negligible with your Ld9 and BsB. The +1 to Toughness is the most popular Big name out there and compared to the rest of the names available it gets an A!

Would I like to see some changes in the errata like a 10pts reduction. Hell yes... but its not going to happen. IMHO it is a must take on any Tyrant
Gruts Sickle, now the difficult one. The rating is slightly tainted with personal favour... I love the gruts sickle in <2000pts game. It lets me run 1 mage (and 1 caddy) and dominate the phase with +7 to casting! Even dwarves struggle against that. The item is situational and is a complete gamble

Just like our Hellheart. While the Power Stone allows you to get two extra dice in one magic phase, Gruts allows you +2 to casting in Every one. The extra power dice also count towards irresistible, something we want to avoid as ogres. (for the most part) I am one of those people you mentioned that swear by the item, I never run a SM without it because it has saved my magic phase all too many time. Yes it has back fired from time to time, but I knew it was a gamble when I put it in my army list. The item can be rate from A to D... same as our Hellheart. When it works its an A, when it fails I will expect a lot of comments here blaming me
Chris