IIIL, XL, and 4XL are all the same glass. When early production of the XL's first came about and were running parallel with the IIIL's, those IIIL's got the better glass (per the President of Isco USA then owned by Schneider). Not much difference, but the Isco versions were reserved for the OEM customers, such as Runco, DPI and myself included. Input aperture and exit are identical in size. There are actually 2 other case designs, and technically speaking, none of these names (IIIL, XL, etc) are "official". They use numeric codes. The names are ours, although the Schneider versions were first to actually get XL etched in the lens. The current XL version, as well as 2 variants of the Isco 4 have a "tube" that sticks out of the front of the lens and does not move. The exit element moves inside this "tube". The older versions of the IIIL have no such tube and are built a little differently. Today, there is only Schneider branding, they did away with the Isco branding and separate Isco models. Not the best marketing move IMO, but they don't ask me for input like they used to (post Schneider).
The DLP Cinema lens is made to tighter tolerances and finer polish. It's bigger but the only one Isco officially blessed for 4k.
There are no new lenses from Schneider/Isco nor do I expect we will see any. They are happy with what they have.
Scott