Many folks find these ultra aged bourbons unappetizing............and I can understand why.........the wood is definitely the major player and they are (at least these two fellows and at least in my opinion) at the edge of abusing their time in the barrel.
I can think of several bourbons that lingered too long in the barrel. They were the last Pappy 23, a Rowan's Creek (I believe it was around 15 years old), a Noah's Mill 15 YO (but not all Noah's Mill), Elijah Craig 18 YO (all of the EC 18 YO's I have had were not to my taste), and one of the Stagg's (it was at least 15 Years Old).
Still, the Pappy 20 (I expect I have had 4 different expressions of this fellow) and several of the BMH (selected, I believe, by Julian Van Winkle, as were Pappy Van Winkle bourbons) ultra aged bourbons suited my palate very well. I think they bring an extra dimension to the world of bourbondom that only the ultra aged have. I have discussed it before several times in this forum. They capture much of the beauty in the barrel in terms of its thick richness, sweetness, and creamy texture, but with a slightly different emphasis.
They moderate the alcohol quite a lot and bring all components into a subtle sweet/dry sip that almost belies it bourbon origins. This is bourbon singing a different tune (and singing off key to many experienced and knowledgeable palates), one I happen to like a lot.
I also happen to prefer bourbon over Cognac and Scotch............but harbor no disregard for those who would change that order. Cognac (which is always in my cabinet) and Scotch (which is always in my cabinet) probably have more afficiondos than bourbon if you count the whole world. There is no substitute for either of those spirits...........they are just different from bourbon, not inferior...........preference naturally being a matter of taste.
Still, I do find both the BMH and the PH to have qualities reminiscent of Cognac in their subtle sweetness and soft sophistication.........qualities that I claim come from long association with the barrel (Gary Gillman has disagreed with this assessment and his is undoubedly a more knowleadgeable opinion than mine............still I persist in my folly because I can see no other reason for this similiarity).
As to the bourbons at hand, I can taste little to differentiate them. If anything, the 27 YO may have a touch more of the goodness of the barrel.........a surprise to me!
Ultra aged bourbons in my opinion, should be evaluated against each other, not other bourbons..............and only then if you care for them.........and you are not under the slightest obgligation to do so, because they rarely come cheap and are rarely (if ever) worth the cost!
Do not go gentle into that good night,
Old age should burn and rage at close of day;
Rage, rage against the dying of the light. - Dylan Thomas