I thought of a fun alternate speedrun route.
If you do guard exit, then single-up exit + quick level zero exit, you get the warp-6 sprite set + kill button in just 45 seconds, and reach level 4 after just 80 seconds total. This is an improvement of about 18 seconds over the current "no gate skip" warp-16 route. The difference is, this particular setup will cause Blind Level 4. And since there are no Princess Bedroom scenes until Level 20, and no break in action, this means Levels 5, 16, 17, 18, and 19 will also be in Blind Mode!
Theoretically, this means the No Gate Skip route could be done in under 11 minutes "easily." But here comes my interesting idea --
How about a Game Genie speedrun, where I use No Gates code (this will start the game with Gate Thief ability, even though the Prince sprite is normal).
This would essentially follow the GT1 Warp-16 Route, demonstrated in my new video, above. The only difference would be that the setup is faster, and the vast majority of the run is "Dark," to be a fun challenge. I think I may do this next, and see how far I can get.
One major difference to keep in mind, is that the Game Genie code allows for ultra-fast Level 4 route, to jump through the middle gate without visiting the first guard. However, some time would be lost at the big drop, since the gate will not make contact, and you will be stuck on the ground for 2.3 seconds, due to stun. (In my No Gates demo video, I also used Invincibility Mode, but that would not be available in a speedrun.)
I suspect this theoretical route would be about 36 seconds faster than the above GT1 route to reach level 4, and maybe 11 seconds faster on level 4, putting a perfect performance around 7:45.000. Having a shorter, less tedious setup, but more nail-biting "Blind" action could make for a good video.
I can imagine the logs on Level 17, and all the jumps on Level 18 will prove quite difficult. While I have memorized Levels 4, 5, 16, & 19, I don't know if I'll be able to get very far into Level 18 without some serious new practice.
EDIT --
I've hit a snag here. Under normal circumstances, whenever you are hanging on a ledge below a closed gate, and attempt to climb up and get denied by the closed gate, one of two things can happen, depending upon how you fell and grabbed the ledge: either you will fall closer to the wall, or farther away from the wall.
We were always careful to do the correct approach for the Warp-16 hole, so that after climbing up into the closed gate, and being forced back down, we always got the variation where the Prince fell farther away from the wall, and this allowed the good Warp-16.
However, the No Gates Code causes the Prince to ALWAYS fall close to the wall after being stuffed by the closed gate. (The No Gates Code does not prevent ALL gate interactions -- you still cannot climb up into a closed gate.) So this eliminates the "good" warp-16 I was hoping for.
So far, the only way I can find to warp is to do the Fast Drop, as we have been doing on level 5a for the FGT route (which does a Logo Reset). However, for this 6/4 sprite set, a fast drop warps to the Beginning of Level 16, not the checkpoint.
I absolutely cannot find a different way to do it. Everything else is a No Warp, or Logo Reset for a strange shaking version of FGT.
So, this theoretical "Blind" run I imagined must warp to the beginning of Level 16. Compared to the GT1 route, this loses about 40.5 seconds (taking into consideration the worse lag for GT1 on levels 16 and 17), bringing my projection back up to 8:25.5, and therefore, probably not faster than the GT1 route.
But then I remembered one more thing! No Gates means no need to fall down in the 2nd room of Level 5. This saves another full 7 seconds, and puts this fun run back on track to be faster than the official route by at least 2-3 seconds!
Add to this the further benefit of doing the full level 16 in the Dark as a bonus challenge, and I think I've got myself an excellent project to work on next, shooting for a sub 8:20.
So to sum it all up --
Using the Game Genie's "No Gates" Code, and doing a very simple setup gets the Prince on a quick start to Level 4. After the Level 4 Warp, the No Gates Code allows for big time savings at the Mid Gate on Level 4, as well as big savings in the 2nd room of Level 5. Further, without any big lag, massive time is saved after the Level 16 Checkpoint, as well as the beginning of Level 17. But counting against all this time saved (simplified setup, Level 4 shortcut, Level 5 improved, Levels 16 & 17 lag reduction), we have to add big time for playing the first half of Level 16. Joyously, the savings slightly outweighs the cost, and this fun theoretical "In The Dark" route should be a few seconds faster than the official GT1 route.