I really love this forum - everyone is so helpful
Thank you for all the replies!
So I was obviously way off about Chinese greens (and even sencha)!
Xell, I did try some sencha, but it was a cold brew version from Den's Tea that was mixed with matcha (comes in tea bags). I quite liked the flavor, but it was a lot more bitter than I expected, especially for a cold brew. In light of your post I'm guessing the matcha's the culprit, not the sencha itself.
Entropy, I was almost embarrassed to admit that my gyo came from Teavana...

I know the quality of their teas doesn't align well with their inflated prices. I will definitely try out jingteashop, especially since you and
JRS22 both recommended it!
JRS22, I'm glad to hear from someone else who is very sensitive to any bitter flavor in teas. It's so difficult to judge subjective things like flavors, and it occurred to me that the cold-brew sencha I tried earlier would probably not seem all that bitter to someone else. For me, though, it's unpleasant enough that I rarely drink it, despite the convenience. I'll be looking into both of those vendors, and I'll be sure to watch the harvest dates.
Oni, thank you for the suggestion - a "Chinese gyokuro" is pretty much exactly what I am looking for! (Although now I can't wait to try other Chinese greens as well) Brief digression: your posts were very influential in my decision to buy some banko clay tea pots last fall
Chasm, yes, I think I have the brewing parameters dialed in pretty well - at the very least, I won't be brewing with water that's too hot. If anything, I probably risk brewing with water that's not hot enough to extract all the flavor, but it sounds like I'll have some room to experiment.
tea-awed, I've read so many sentiments similar to yours: "pleasing bitter edge" that gave me the impression that Chinese greens were universally bitter. I just didn't realize it was only a matter of brewing to get (or avoid) that taste. Is young sheng pu inherently bitter or can that also be brewed for a milder taste? I have some samples from YunnanSourcing.