Check out this comparison of two Noblet alto saxes.

And here is a history of the origins of Noblet and LeBlanc

Vito Pascucci was Glen Miller's band instrument repair technician in the American armed forces during WWII. Vito met George Leblanc while in Europe. They became friends and vowed to start an American branch of the Leblanc business after the war. Leblanc kept his word and after the war (1947), started sending Vito Leblanc clarinets to be assembled in the U.S.A. by Vito in Kenosha Wisconsin. A short time later he began sending these saxophones too. They were Noblet saxophones. Leblanc had bought Noblet and the Beaugnier music instrument companies years earlier.

"Leblanc owned the Beaugnier Saxophone Company of Mantes. They manufactured the complete family of saxes but their production was very, very small. Their factory was located across the street from the Selmer factory in Mantes. Mr. Beaugnier made wonderful instruments, but unfortunately their cost of production was so high that eventually Mr. Leblanc closed the plant. We still have all the tooling, but labor costs would be too high."

"The sound is excellent...Very French/Selmerish and full with a centered quality."

There is also an 'on or off' selector lever behind the G# table key for choosing whether you want to play with the G# / C# articulation on or off. Most sax's are either articulated all the time or not at all. It has a fingernail file style surface on it.

Vito with Glenn Miller, somewhere in England during World War II. Letters from Vito
Reminiscence by Dr. Pascucci (G. Leblanc Corp.)
b. 1922 - d. 2003

Foreword by Paul R. Coats:
Mr. Vito Pascucci is CEO and co-founder (with Leon Leblanc) of G. Leblanc Corp of Kenosha, Wisconsin. Leblanc has brought us Leblanc and Noblet Clarinets, Holton brass, Martin Saxophones, Yanagisawa Saxophones, and of course, the instruments with which many of us started our musical careers, the Vitos! Here are excerpts from his letters:

Soon after the war I met Mr. Strasser, the remaining owner of Strasser, Marigaux and Lemaire. They were very successful with their Marigaux oboe. It was made in Paris in the early days; now in La Couture Boussey where we have our Leblanc/Noblet factory.

Yves Rilba recently retired. That seems to be the goal of all Frenchmen--to retire as soon as possible--Yves is 60 years old. He has done a wonderful job for SML. It's interesting that they moved to La Couture in 1975 when they bought the Malerne business. Mr. Malerne was a Noblet foreman in 1904. He played clarinet in the La Couture Municipal Band and Mr. Georges Leblanc was the director. Mr. Leblanc would complain that Mr. Malerne's intonation was not good and after he started his own factory it got even worse! Because they were good friends, Mr. Malerne enjoyed upsetting Mr. Leblanc and this was one of their ways of having fun.

The SML company was sold to Seeberg, a Chicago juke-box manufacturer. I negotiated with the principals of that company for four months hoping to acquire it, and it did not work out. What a small world this is.

Hopefully some year we will again resume the production of the Leblanc System saxophone and that we will be able to produce the type of sound you enjoy and found in the old SML saxophone.

Leblanc owned the Beaugnier Saxophone Company of Mantes. They manufactured the complete family of saxes but their production was very, very small. Their factory was located across the street from the Selmer factory in Mantes. Mr. Beaugnier made wonderful instruments, but unfortunately their cost of production was so high that eventually Mr. Leblanc closed the plant. We still have all the tooling, but labor costs would be too high.

The above is from Paul Coats
http://www.saxontheweb.net/Coats/vito.html

Vito Pascucci and the Leon LeBlanc made the decision to market the LeBlanc French instruments under two names.
The top of the line instruments got stamped "G. LeBlanc / Paris".
The step-up, mid-range instruments were engraved "Noblet".
But there were no saxophones then made by LeBlanc, so they bought them from saxophone specialists Beaugnier, in Mantes, just down the road from La Couture.
Beaugnier had produced some of the "Rationale" model LeBlanc saxes before the war, so they were the logical choice to build numerous saxes for distribution in the US.

The "LeBlanc System" (or "semi-rationale") were the top-of-the-line. They were introduced in the late fifties.
The same dimensions were used for the step-up saxes stamped "Noblet". The cheaper models got nickel-plated keywork. A more expensive Noblet was given chrome-plated keys and some earlier models were fitted with gold-lacquered keywork.

The Noblet/LeBlanc saxes had full rib construction keywork and the spring action is somewhat light and fast. The tone-color is refined, similar to the Selmer Balanced Action. Intonation is always very good.
Often the Noblet came with a cartouche on the bell brace or on the neck, above the tenon, with images of Georges and Leon LeBlanc on it.

Links:
www.saxontheweb.net/Coats/vito.html
http://www.gleblanc.com/history/index.cfm
http://www.simplysax.mynetcologne.de/Vito.htm
http://www.saxpics.com/the_gallery/Leblanc/