From small speakers to floorstanding

My new audio space is big... 20w x 35l x 8h. I use it for everything from HT, gaming, and vinyl -- it's a do it all kind of space.

I've tried out 2 sets:
Orb Audio
Aperion 5T

The Orb Audio was an easy test -- I know this setup very well and really like them for what they do. I ran this setup for about 3 years and it's quite enjoyable. For the new room size, I'm asking quite a bit.

Aperion 5T -- They are nice too, but only a small incremental improvement over the orbs (yah, I know... surprised me too). I'm hearing some congestion in the midrange. Can't really describe it just yet, but I do hear some veiling. The Orbs are much more detailed in the upper midrange and treble (almost to a fault). I think the 5Ts are out due to the only small improvement (...and even that's debatable).

I'd like to upgrade to a larger speaker set because I have the space. Problem is... where do I go from here? I know I'm getting an SVS-Ultra sub at some point, but what L/R combo do I use? Music production is first. HT IMO doesn't have the high level of sensitivity that HiFi does.

Budget for L/R is whatever it needs to be in order to hit the sweet spot. I don't mind paying for exponential improvements, just don't want to spend 10x for only incremental. Know what I mean?

My listening room is 16.5 X 34 w/cathedral ceilings. !2" Tannoy Dual Concentric (HPD 315's, ca 1975, Hard Edge surround conversion, custom 150 liter cabinets, custom crossovers) fills this space, in a very satisfying way.

Tannoy's current Prestige line has several models that would suit your needs. Kingdom Royas, Canterbury SE, etc.

I am able to drive them with a 9Wpc SET 300B, to a level beyond what I want to listen to.

The versions w/15" woofers may be what you need in your room. Tannoys are very good at reproducing the scale of music, which makes them ideal for large spaces.

How much time did you give the 5Ts to break in? It frequently takes 100+ hours for a speaker to begin to open up and show you what it can do, and frequently a new speaker sounds congested, lean, dull, etc. until the internal components burn in and open up. Frankly I'm surprised they didn't offer a significant improvement over the Orbs, which again leads me back to maybe they're not burned in yet. You might call Aperion and ask them about this as well.

That aside, if you're getting an SVS sub at some point in the future you could demo their floorstanding speakers that have gotten good reviews. Assuming the Orbs do a good disappearing act and image nicely and given the size of your room I'd look at the Joseph Audio RM25XL or perhaps something like the Thiel 2.7 or Gallo 3.5. If those don't make exponential improvements over the Orbs -- well -- maybe you're just an Orb guy. Tough to make firm recommendations without knowing specifically what you're looking to improve (other than size) and what aspects of sound are most important to you. Hope this helps and best of luck.
Hmm. The Tannoy's are way out of my price range.

I gave the 5Ts about 2 hours. I bought them openbox, so I assume the breakin period is well on it's way. I wouldn't imaging that open box is a fresh set of speakers, but I could be wrong.

Maybe I'll face them together, take one speaker out of phase and run them overnight and see what I get the following morning.
I wouldn't assume that the speakers were broken in just because they were open box. Open box could mean anything, and what you heard seems an awful lot like a speaker that hasn't opened up yet. Like I said, you need to give them at least 100 hours (and preferably more) of good volume playing before making any serious judgements. Running them out of phase overnight will not likely bring you to full break-in. Stop rushing this. Give them time before making any conclusions.
Yeah, that is a pretty big room, and the 5T is a pretty small speaker for a room that size. Also, I'm not sure how far from the speakers you sit, but with only an 8 foot ceiling, there is ample opportunity for a lot of reflections from the ceiling as well as the floor, so it may be that congestion or the sound could be mitigated with speakers with a more narrow vertical dispersion. I'm certainly no expert, but just a thought. The Monitor GX series does employ a ribbon tweeter, which I believe may have the more limited vertical dispersion. Perhaps something like this: