To address Craven's question, I think by first-hand, he means by someone who has actually played on these horns, not just second-hand information obtained without personal experience.
I can give you my personal experience with current production Selmer saxophones:
Tenors: I've used a 2005 Selmer Series II tenor as my main classical tenor for the past 6 years. It has a great focused core sound and very solid intonation. I've also spent quite a bit of time with both the Series III and reference 54 and 36 tenors as well. I feel like I get a bit less focus from the reference and series III but they are more free blowing. The sound is less plaiable (flexible) on the Seris II which is good for most classical situations where I want an even tone up and down. For my classical playing, I prefer a touch of resistance and I love the more focused sound. For my everyday playing and jazz gigs I use a 1958 Selmer Mark VI tenor. I feel like I can get this Mark VI like sound from a Series III or a reference tenor more so than I can from the Series II. These horns have a more flexible core and are more apt to tone shaping. They also have more of a spread which works great for jazz where you use a lot of subtoning, but not so great for classical playing where you almost never use subtoning (especially in traditional classical saxophone literature). Listen to classical recordings of Fred Hemke for a great example of what the low register on tenor should sound like in traditional classical music.
Alto: My wife uses a Selmer Serie III alto (sterling silver) for all of her classical saxophone playing. I don't do as much serious classical music on alto as I do on tenor, but I do enough of it to have a solid opinion. The sound of the series III alto is definitely a nice pure sound with plenty of focus. A good series III also has a good resistance point for classical playing. However, I've never been 100% satisfied with the overall tone I get from a Series III alto. It feels just a bit blatty to my ears (if that term makes sense). By that I mean, there seems to be a certain edge that I have a hard time getting rid of with a Series III alto. I find that to be even more the case for a series II alto. The reference 54 alto has more of a spread sound and is also not a great classical choice for me. However, Jon, in our shop (Saxquest) is a trained classical player and he uses a Reference 54 exclusively for classical playing. So a lot of this is personal choice. For jazz playing, I use a Selmer Mark VI (1957 vintage). My wife uses the Selmer Series III for jazz as well as classical. I've also used her series III on a few jazz dates and I have to say the horns worked quite well. Intonation is definitely very solid. Having a professional set up makes a huge difference on a new Selmer alto. There are a few things that can be done by an experienced repair shop that help issues such as intonation, buzzy C and the low register gurrgle. So, make sure you buy from a shop with an experienced repair tech who knows about these issues.
Soprano: This one definitely comes down to a personal chioce. There are some people who swear by and others who detest every type of soprano made by every manufacture. So, take any soprano review with a "well, let me try for myself attitude". That being said, I'll relay my experience with current production Selmer Paris sopranos. The series III is in general very good. Right out of the box, some of these have difficulty speaking in the palm keys with a full voice and a few have a problem in the mid-register speaking between mid register F and G. The sound colum become unstable and you get a gurgle. This issue is a difficult one to deal with from a repair standpoint, so best to play test first and just avoid buying one that has this issue. The series III has a nice warm sound and works well for both classical and jazz. The series II soprano is also a wonderful horn, but has a different sound and not quite as solid intonation. Its perhaps a bit brighter overall and a little less consistent up and down the registers. But I do like the feel of a series II for jazz. Still, my preferred soprano is a Yanagisawa 991 for both jazz and classical. I've also recently started spending quite a bit more time with a P. Mauriat System 76 series II.
OK, I hope this information is something along the lines of what you were looking for. Please feel free to ask any other specific questions or feel free to call Saxquest and talk to any of our experienced sales staff. All of them are professional players and all have spent a lot of time with current production Selmer saxophones. When considering Selmer saxophones, its always a good idea to consider buying a used horn as you can save a bundle and there are several on the market from which to choose. Just make sure you buy from someone who allows for a trial period and has a fair return or exchange policy.
Best of Luck!!