Fwiw, I'm a total noob, but I am a hedonist in many things. Only most lately, Straight shaving. I ordered the Penhaligons Endymion with my first kit, but upon advice that the C.O. Bigelow was also very good, found it deeply discounted at B&BW and went deep. I've been alternating between the two.
First off, the Bigelow comes from the tube in about a 5mm diameter. The Penhaligon, maybe 2mm. I find that a 1" long strip of the Bigelow doesn't need much water at ALL before becoming soupy, difficult to contain within the brush when brush is held knot down, and doesn't feel "rich" going on, no matter how much I whip it in the cup.
A similar length of the Penhaligons, requires quite a bit of water, a little at a time, and produces a very rich lather. So rich, if I bother to leave it on while I strop, it often is dry and comes off like snowflakes. Whereupon, I have to re-lather. Another thing, is that the same amount of penhaligons, when I scrape the brush on the side of the bowl, will produce more than enough base to rewhip with additional water for a full second, and then again even a third pass.
While the Penhaligons is triple the cost of the Bigelow, I'll go out on a limb, and say that it probably takes almost 3x as much Bigelow to produce the same lather, and it is of inferior quality lather at that. I'll be looking to buy more Penhaligon when I see it at a good price.