I have a good-quality straight soprano and a super-cheap curved one.
The straight one has better intonation, but I am sure this is due to build quality, not shape.
However, the curved neck for my straight soprano has poor intonation compared with the straight neck.
I’ve had a few sopranos - mainly 'expensive' ones that you'd expect
not to be poor in intonation:
Yanagisawa 901 straight and 991 curved;
Selmer SA80 Series 2 (straight);
Academy (straight).
They all played well in tune - but to quantify that, I was a very experienced player before playing a soprano sax and naturally make any adjustments needed with tongue/throat. Ergo, nothing was
bad enough for me to notice any changes feeling un-natural or especially big.
The curved 991 was years ago and I remember it being a nice horn but for me the whole curved thing just didn't feel right. I hated the way it sat/felt in front of the body and sort of swayed about.
The 901 I bought for a tour five years ago and it played well but I found it thin - (smaller bore?) - so I sold it and got the Selmer. The Selmer is.. well it's a Selmer, which is why I bought it. Got it 2nd hand, one black and gold to compare it to (hated that).
The Academy I got from Robbie maybe 15 years ago. He used to come to a jazz residency I had with a band near where he lived. He let me have it for the price it cost him to import it (£100) and was interested in what I thought of it. Being Chinese, they weren't consistent (gasp and shock horror!), but I couldn't believe this one. The mouthpiece in the box was nasty, or perhaps
really nasty, so I bought a Meyer. This might have been ill-suited to the horn, but I'll come to that later.
The intonation was pretty much 'Bob-on', no complaints at all. The sound was really nice - not all bright and 'oboey' (sorry if you like that - matter of taste). It was very playable - apart from one thing: I used to get a headache from playing it! Maybe tension in the shoulders, or maybe the mouthpiece needed to be more open and it was all a bit 'closed' for me. Anyway -
it was £100!
Later on Robbie asked me to help him develop the Jericho brand (purely from a players point of view, as Steve Howard had given advice from a build quality perspective) which was really exciting as I could suggest a tweak and it would appear on the next batch from China about six weeks later. I think that one such tweak was the thumb octave key - it was placed at a 12 o'clock position and I asked for it to be moved to the 1 o'clock position.
I was able to go and rummage through Robbie's stock and pick one of each horn. They did vary, but were getting better. I might have had a Jericho soprano but I can't remember now. The whole journey was cut short en route to its prime with Robbie's unfortunate death. Robbie was a really lovely guy, and a huge character. Great times...
I saw something written on here about them stopping selling the soprano being of quality control issues - there were bound to be some, but it wasn't as simple as that - because it was cheap and small, lots were being bought as a first instrument for very young kids. There are always exceptions to a rule, but most experienced teachers and players would not advocate the soprano as being the first instrument to learn on - it's too hard.. too definite in its demands and certainly not forgiving. This inexperience, and lack of progress often led to horns being returned as "defective", but were nothing of the sort.