The box the brushes came in was waiting for me when I got home, and my first impression was, "Wow, these are nice." After lathering both brushes up and messing with them a bit, I want one in a 22mm knot in B/W ebony.
I lathered both brushes up and let them bloom. Below are photos showing the ubiquitous Crabtree & Evelyn Best Badger Brush on the left and a Simpsons Chubby 1 in super silver-tip on the far right. I tested both Mt. Tamalpais brushes out on Mama Bear rosemary/mint, which cut the wet dog smell the first go. Both brushes did very well on soap, and noting how long it took me to get all the soap out, I think I could have gone three passes on one brush-load. I'll give them a whirl with Proraso in the morning. The red palm brush didn't lose a single hair, but the spalted maple lost two and no more.
As an aside, nothing reeks when wet like the Burma Shave $4 natural boar brush at Wal-Mart, so these smelled like roses in comparison.
In regard to density as compared to the Chubby, the Mt. Tamalpais brushes easily meet it, and perhaps surpass it. It may appear in the top-down photo as though the Simpsons looks denser, but that's because the tips are considerably whiter, which the photos don't really show. I paid approx. $150 shipped for both brushes (keeping in mind that these brushes are huge), and a new Chubby 1 in super is $185, plus shipping (I bought mine used). The Chubby is scritchier than either Mt. Tamalpais brush, and the red palm brush is particularly soft...but nowhere near floppy. I like the looks of the spalted maple brush better (can you say Rooney?), but I think the red palm brush will actually see more use.
I love my Simpsons Chubby1, and it'll remain a staple in the brush rotation, but in my opinion, Dan's brushes are an amazing deal. Strong work, Dan.
Day two:
If you're used to smaller brushes as I am, the big boys have a learning curve. I used the bigger 28mm knotted brush with Proraso cream this morning, and it made tons of lather once I got in the groove, but I found that the bowl I use for cream way too small, and the brush holds so much water that I got my cream/water ratio off initially. It took some time to get it right. I don't think that's a problem with the brushes at all; rather, it's a matter of me getting used to the new size. I think I need a cereal bowl for these guys.
(Bottom photo: NW=red palm; SW=C&E BBB; NE=spalted maple; SE=Simpsons Chubby1)