OK, I just ran through Yellow again, without reverting to savestates (except for once against Sabrina when I forgot to use 2 X Speeds instead of 1 and got raped by Alakazam), using Zapdos against Giovanni's Dugtrio.
Time: 2:44, the same time I got the first time. Granted, I got lucky a couple times (Misty could have beat me, but used X Defend), but overall it was pretty clean. I think I need to buy more X Items next time so as to be safe in case I do get critted so it will be possible to revive and set up again. this time I bout 9 Z Accuracys and Speeds, and 2 X Attacks, so like 12 each acc and Speed and 4 X Attacks.
I dealt with Koga by using Horn Drill instead of Rock Slide, since Venomoth was a 2HKO even with an X Attack, and I didn't need to go to the store beforehand since I have the Pokeflute, although it might be safer to do so in case you get double critted by Psychic (with a Special fall).
This time can still be cut down, by the way. I made a few path mistakes again, could have caught Nidoran faster (although I did catch it at L6, which saved some time, and I also caught Pidgey while looking for it too), and I went to the Mart/Safari Zone before fighting Koga, which may not be needed. I also made a switch to Pidgey during Giovanni's fight on accident, which lost me a minute or so. I'm thinking that an exceptional time would be 2:38 or 2:40. I did score in the Vermilion Gym, getting the trash cans on the first try, which could have made up several minutes, which is why 2:40 would be very good in my opinion.
I will be putting together a rough guide for Yellow using Nidoking, kind of like Myrrh's unfinished one (Cough Cough) for Red. Look for it here and on the MSN Alpha Fan group page in the next couple days.