OK, I played with the drawing a little. I made the shower a little bigger and moved it next to the tub. The storage is gone but you get a closet outside of the bathroom. That's even more storage. If you are looking to have maximum storage inside the bathroom, it's not the best answer though.
Pros and cons:
1. Bigger shower. In plan H6 you had a 60"x50" shower. In plan I the shower is only 36"x60", and the neo angle further reduces the size. With the bench cutting 17" and the neo cutting 12" on the length (I assumed 20" on the return panel, 22" on the 45 degree panel, and drew a line at 32" width since beyond that it's dead space for showering), your shower is only 36"x30" effectively. That's kind of small.
2. You get the chance to put the bench on the neo side, as an extension of the tub deck. Not that it's athetically or functionally better per se, but with the bench on the neo side you can have the shower door hinged to the wall on the other side. Now that's a big plus, IMHO. If the shower door is hinged to another glass panel, it's not stable, unless that panel goes all the way to the ceiling so that it's secured on three sides. Or you'll have a header, as shown. Having the glass to the ceiling increases the cost of glass significantly, and there will be additional cost for ventilation and shower ceiling treatment (tile the ceiling). Having the header, IMHO, defeats the purpose of frameless shower. And usually you still have to increase the height of the glass at additional cost. So, if you can have the shower door hinged to a wall, don't put it between two glass panels.
3. You get the wall space between the shower and bathroom door to put your mirror. It's close to the dressing area which makes most sense, and by putting the mirror on the long wall, the tunnel feeling will be aleviated.
4. More storage, although it's outside of the bathroom.
1. You lose the storage between the shower and tub. There will be less open space in that area.
2. The bench on the neo side is a little awkward. Maybe you can have a shorter bench like shown in the other drawing, which also opens up the space between the shower and tub. But then, the bench is kind of small, and maybe not too comfortable if you sit on the bench to take a shower.
3. Extending the wall next to the bathroom door could make the "tunnel" feel narrower, although having a mirror will help.
In plan I, if you are ok with the shower size, building a wall next to the bench can address two things: the mirror and the shower door hinge. But that wall, same as if you opt for a closet, could make the room "feel" narrower.
mediaman, maybe maybe plan H6 is not that bad at all. In plan I the cost increase of the glass shower door may be close to what you need to pay the plumber in H6 (custom vs. stock and significant bigger glass). Plan H6 also utilizes the floor space the best, creates more balanced foot traffic (shower on one side and the rest on the other side), and does not have the tunnel feeling. The only thing I'd suggest other than relocating the toiler is to have a bigger entrance. My powder room has a 24" door, and I think it's small even for a small powder room. To accommodate a 30" door, the shower size needs to be reduced to 56"x50". I know it's a big sacrifice, but the shower is still roomy. With a 17" bench, the opening is 39". You don't even need another glass panel, just one pivot glass door hinged on the wall is good enough. BTW, the wall next to the bench doesn't need to be full height. You can have it the same height as the glass door if you like (I still like full height though). And the full height mirror? Behind the bathroom door.