TubeNet

Answer to original Question:
"Elongated 1st"-type 5th valve is VERY useful / necessary on a big horn, as others have stated already.
So is a well-accessible 4th valve slide or main tuning slide / Trigger.

As to the weight:
When I need to put the horn down frequently, I rest it on the bottom bow and stabilize it between my knees / one hand on top bow.
This is great during long rehearsal sessions and on crowded band stands. (Less danger of someone´s foot on bell flare).
Horn can be lifted with straight back, no bending forward or sideways required, which is a good thing, says my spine.

I find 5th valves are becoming increasingly important as a lot of contemporary composers are writing for notes that really require them. 4 valves get you through a symphony gig 99% of the time is pretty true, you can play the E's in Fountains or Ride at 4-2-3, the Eb's in Prokofiev 4-1-3, same as the D# in Planets. A solid E or Eb is about the bottom for the bulk of the actually played symphonic rep it seems. I find in the contemporary college wind ensemble, however, that composers are regularly asking for D's, Db's, Pedal-C's, Pedal-B's, etc. notes that (depending on your chosen key of horn) are really only practical with 5 valves. I've noticed this change to needing to play much louder, and much lower, in wind ensemble music pretty pronounced, especially after returning to college some 8 years after my first go around.

Every horn I build (regardless of length/pitch/key) gets a 5th valve, whether it likes it or not.

I'm perfectly fine 'pumping' the 1st slide on two or three of my tubas for finer intonation
And good, easy response with the right tuba + mpc combo also goes hand-in-hand with good intonation. Easier response makes for easier intonation, as long as nothing is too 'wacked' out of tune.

tubeast wrote: So is a well-accessible 4th valve slide or main tuning slide / Trigger.

^ Triggers (on the most needed/useful slides) would be nice on more tubas Just as good as a 5th or 6th valve, imo.

bloke wrote:
As to valves, I've been reading all of the comments and am considering removing ALL valves and and considering installing just one L-O-N-G slide (located where the first valve slide is normally located) on all of my tubas...I'll just need to get a ceiling clearance report from each venue ahead of time, and hire a "slide assistant". I'll report back later, regarding any improved response/intonation, which are anticipated.

^Since you like more valves, maybe instead, you can install a 7th or even 8th valve on your 6-valve F. That way, all main fingers on both hands will be 'busy' while playing, kinda like a woodwind player!

any of youz guys saying youz don't need a fifth valve iz juzt jealous and trying not to show it.

everyone knows fifth valves have more fun

bloke wrote:I could cut blokeplace with a 42" riding mower...or (possibly, were I as big and strong as some of you National Sousaphone Championship finalists...??) a manual-powered push-mower.

I choose to do neither of those, as I have access to easier-to-use equipment.

And that’s the ballgame if it’s available why not use it...

JJ

bloke wrote: Some of them feature saggy pitches all the way down to the 1-2 fingered pitch (even with the #1 pushed in all the way). The 5th valve (alone) - very often - is a solution to this problem (the otherwise 1-2 fingered 5th partial pitch)...and that's not a "low range pitch that I'll never need".

Would a 6th valve (flat half step) work as a 1st valve substitute?