The IANTD course progression isn't really that tricky.
The deep diver and the advanced nitrox together make up the entry level tech program. I think they could do away with the "deep diver" but it is air only and no staged decompression while the advanced nitroc isn't just air and does include minimal decompression. IMO, someone who wants to go as far, or further than advanced nitrox, doesn't nee the "deep diver course" for anything. So...you can combine then and it adds to the divers experience in that they have to do some more dives but there is a big overlap in skills and objectives.
They have recently added the recreational trimix courses but lets set that aside for a minute.
The "technical Diver" course is sort of like the TDI Advanced nitrox. 170 on air with 100 O2 allowed for decompression.
Normoxic trimix...200 ft with one decompression gas and it can be combined with the tech diver course ans presto-chango...no deep air.
Then of course, the advanced trimix which is self explanatory.
Now back to the recreational trimix classes...they can be combined with courses like advanced nitrox and, for those who care, you don't ever have to do a dive with an END below 80 ft.
They also have the "decompression specialist" class whic is classroom only and, if taken, lets you do the rec trimix/advanced nitrox combo down to 150 with 20 minutes of decompression and use 100% O2 for decompression.
ok, maybe more than what you really need but burried in there are a lot of options, no need to dive deep air and it isn't really all that hard to understand.