Here is Raytheon Part 2. The description of the prior tubes matches this pair exactly with two differences: these are branded GM (as in General Motors) instead of Zenith, and they have round style plates instead of ladder box plates.
So I'm going to get right to the meat of this impression post and come out with it: yes they sound different, mostly in one key way. The biggest question on my mind was whether or not round plate tubes have a different presentation vs. a square plate style such as the ladder plate or t-plate. At least as far as these two tube cousins go my ears say yes. There is a distinct difference in how the soundstage is presented and rendered to the listener. I found the ladder plate tube to have a headstage that was distinctly foward, placed in front of your head, with a stage shape that is more wide than deep. This round plate, on the other head, feels like it centers the sound ON your head rather than in front of it, producing less of a stage effect and more of an immersion effect. There is a bit less soundstage width, but a great deal more front/back depth. I think you can see where I'm going with this: yes, IMO, the shape of the plate seems to correspond to the shape of the soundstage. I have given a great deal of thought about whether or not this is real or if I'm just experience a psychosomatic perception and the difference is just expectation fulfillment. But I think what I'm hearing here is real, again at least for these two specific tubes. I consistently am given the impression by the round plates that musical information is being presented or projected BEHIND me, and I just didn't get that same impression while listening to the ladder plates.
I really can't say whether one would be better than the other. It's really down to the listener's preference. For example if you consider a stage presentation such as what you would hear in a live concert with the music coming at you from the front to be more "correct" you might prefer the ladder plate presentation. If, on the other hand, you want the music all around you sort of like the music version of being in a planetarium then you would probably really like the round plate.
Beyond this the presentation within the soundstage is also somewhat different. I found that, while stage width is not wider, the sense of space between notes is more prominent with these round plates. It also feels easier to listen "into" the notes and gives a greater sense of depth to the sound.
The rest of the differences are much more subtle. Tonally they are very close but not identical. I find the top and bottom end here just a tiny bit rolled off compared to the ladder plate, and it's a bit more mellow throughout the top end. These roundplates tame the Beyer treble completely which means they're a pretty mellow tube overall. I also find them a tad bit more polite dynamically, but the really great spatialization from the soundstage presentation makes up for this in it's own way. I would characterize it overall as similar but a touch more "vintage" than the ladder plate was. In a blind test I don't think I could tell the two apart just from judging tone. Overall this tube is very easy to listen to, but with faster higher energy music it can come dangerously close to being boring at times because of how laid back and even handed it is. The difference in dynamic energy between this tube and the Sylvania engraved base for example is pretty big, those are two very different flavors.
I would rate resolution at least as good as the ladder plate and because of the 3D soundstage probably better. Timbre is great here because of the texture information being conveyed, but even when it's just a single note such as a single bow stroke of a violin I'm struck by the "roundness" of the note and how much depth it seems to convey.
Overall there's a strong familiar resemblence between the two Rays but the soundstage and imaging difference is key and is what lends these two tubes different characters. I like both and am happy to have both in my collection. If you pressed me about only keeping one I might whisper "ladder plate" just because I was really enjoying the overall presentation of them towards the end of my listen the other day. It felt like they could do no wrong as far as my preferences for tone and balance were concerned. I think the roundplates are almost too polite and even handed at times, but every once in a while the soundstaging and how the notes were presented would really strike me as something special and those moments were engrossing so they absolutely have their own appeal. Better to say I'm glad to have both tubes.