In this interview Les states that he used the Hot Tubes to "sweaten up" his tracks on the Brown Album.

En el video sobre la grabación de Fuerza Natural (minuto 10:04) se lo ve a Gustavo utilizando el Electro Harmonix Hot Tubes para grabar unos arreglos (interpretados por Gonzalo Córdoba) en la canción "Dominó". Este pedal también formó parte de la Pedalboard para la gira de Ahí Vamos (2006/2007).

In the bottom right corner of this photo, Brian's Electro-Harmonix Hot Tubes can be seen.

Used on Tales From the Punchbowl and Brown Album, as stated in two interviews archived on the fansite Jim Wade's Sucky Primus Page.

"CyberFunk: Primus go multimedia on their juicy new album, TALES FROM THE PUNCHBOWL"

And then I have piles and piles of effects, too many to name. I'd just start plugging and unplugging things. My main sound was an Electro-Harmonix Hot Tubes, going through that Boogie, or sometimes through an old Ampeg Portaflex. The super-distorted, crazy stuff is usually the Boss Metal Zone pedal with the wacky EQ in it. I used some harmonizer on "Professor Nutbutter," as well...I hope you're going to edit this to make it look like I know what I am talking about.

"A New Kind of 'Brown Sound'"

Les thumped and plucked his treasured Carl Thompson 6-string fretted and fretless basses, which he tunes BEADGC . On “Over the Falls” he used “an old no-name electric upright that sound amazing.” He also plugged in an Italian-made, Hofner-style Eko. “I’d always wanted an Hofner,” says Les, “but the Eko just smokes the Hofner--and it cost $250! It has a real nice percussive attack.” His amp? A small solid-state Gallien-Krueger, which he would occasionally sweaten [sic] with a Hot Tubes, a Systech Harmonic Energizer and the tremolo filter on his ADA preamp.

Anton Newcombe uses the Electro-Harmonix Hot Tubes Nano pedal to add vintage color to his guitars, as mentioned in his Twitter post.

"Outboard gear is a TLA Indigo EQ2012 parametric EQ, which is very nice, SPL Vitalizer and Transient Designer, which is fantastic for shaping the front of the note; if you want things to sound a little further away you just make the attack a bit softer. The TC Gold Channel is a nice mic preamp; my TC M3000 is a beautiful reverb, very true. The FAT PCP330 vocoder is something I use all the time, and I like the FAT Resonator. The Electro-Harmonix Hot Tubes is very cool, as well as my Bob Moog Moogerfooger. I use the Hot Tubes as a kind of mastering box, for pianos, anything digital that sounds a bit plasticky goes through it. It's a fuzzbox, it adds a bit of grit. If you listen to the final track on Memoryhouse, 'Quartet Fragment', you'll hear it on a 60-piece string section. The drums on the track 'Arboretum' on the Notebooks also went through this."

Amir Derakh uses the Electro-Harmonix Hot Tubes overdrive pedal, as shown in a photo on his Facebook page.

Can clearly be seen in this tweet from 24 Oct 2016