I've ordered three of them in 80:20 "gold" brass - to replace the three original ones. (Water tends to collect in this quite-a-few-cubic-inches circuit - even after emptying the circuit, once the instrument is set down after a playing session, and cools off.)
Christian (Miraphone boss) knows that I've always been a fan of this model, and I could visualize his grins (as well as his pride in the design) in his reply to my order, ie. happiness for me, as well as pride in his product.
No kaiser/orchester b-tuba is going to be as nimble as a euphonium or even a very slippery E-flat or F tuba, but I believe this is about as good as it can be - particularly with everything - on the #1 slide - micro-tuning within a two-inch sliding range, and the vast majority of pitches all in one place, on that slide. With an instrument of this size (valveset and bugle) "timing" and "absolute "buzz accuracy" are even more important, as well as (something I learned - decades ago - from someone who is probably nearly universally admired by the tuba brotherhood) - even when playing high-velocity passages - "not being in a tremendous hurry to turn the rotors". I'm still experimenting with minor slide-position adjustments. I'm finding that a generous pull on the middle (of three) #4 circuit slides (as well as a pretty generous pull on the 5th circuit slide) allows the "low F" and nearby pitches to be "down to" tune - even when played quite loudly). With that #4 circuit length, just-below-the-staff C is "just" on the low-side of "in-tune" (equal temperament - played softly), and that allows for the neighboring B-natural to be played nicely with valves 2-4. NOT pulling the extremity (upper/lower) #4 slides at all keeps those slide bows out of harm's way, and I've worked out a tuning "system" - with this instrument - whereby the only pull for upper #4 would be for the (unavoidable, with a 5-valve system) 5-2-3-4 "double low" C...(which almost never appears in written music).
They built the #2 slide somewhat short (C length...??) so that one requires a generous pull for the A overtone series to be down where it belongs...OK: fine.
Again: I'm going to slightly reconfigure the (quite short, on one side) #3 slide, so it's not hanging off at the brink for good 2-3 tuning.
Finally (as posted in the main forum), I'm going to (and this is what I had to do with my new-to-me euphonium, and which transformed that instrument from "worrisome" to "delightful") shorten the main slide bow - mostly on the large side. Cosmetically (at least, to me) that tapered bow appears a bit off-kilter, and I'm probably going to remove around 1/2" from the large side of that bow, stretch it out to restore the alignment geometry, and re-taper the large end. When playing in this room when the temperature is in the upper 60's F., this instrument plays "just" up to A=440, with the main slide ALL the way in. When this room is in the lower 70's F., it offers me a scant 1/8th inch pull - for the same tuning. Though I'm NOT using some extra-deep mouthpiece, I AM using (what I would label as) a "regular-deep" mouthpiece, and I'm just not willing to change the resonance (with some shallower mouthpiece) to avoid altering the instrument's length.
The 1/2" (plus, possibly, 1/4" from the small side) will allow me for some "playing cold"/playing-at-A=442/playing-with-soprano-instrument-"music-lovers"-who-play-sharp-when-high-and-loud push room. All of this rhetoric having been typed, it won't be prudent to cut the main slide tubes, as they are actually (particularly, for a b-tuba) somewhat short already.
Though I have some same-size BRASS inside slide tubing (21.2mm i.d.), I ordered a 3-1/2" long piece of NICKEL-SILVER to be shipped with the bows, as I'm (only very slightly, per main forum thread) reconfiguring the #3 slide, and would prefer that the tubing material be consistent with the model.
I may or may not (??) take the #1 slide apart and shorten it's bow. The 2nd space C (very subtly flat with the #1 slide all the way in) issue is very marginal. Knowing me, though
, I'll likely shorten it - probably by 1/4" x both legs. That having been said, as it is 1-2 B-natural is "on the money" all the way in, which provides a fairly handy "bookmark". 
I'm tackling more-and-more difficult vocalises, each day.
bloke "tackling as many as six sharps - plus double-sharp accidentals - with approximately 12th-grade-level B-flat tuba reading familiarity...but the tunes are predictable, as are all of the finger patterns...' sure is a ton of 2-3 valve combo stuff, in those keys."
