I gave up on "waiting for H4350," partly because as I get, ah, more mature I'm not as willing to continually search for scare components or ammo, which is about the only way to find them. And even when you find some, if it's something you use a lot (whether H4350 or .17 Mach 2 ammo) then it's only a relatively short while until you're looking again.
Which is why I quit shooting ground squirrels with my CZ .17 M2 and sold it, along with what ammo I had left, and why I started trying substitutes for H4350. Right now the leader is IMR4451, partly because it's so similar to H4350 the data is almost interchangeable. In fact Hodgdon's on-line data lists the maximum loads for 225-grain bullets in the .338 as 69.5 grains for H4350 and 69.4 for IMR4451, with an 8 fps difference in muzzle velocity. Have also thoroughly tested IMR4451 in cold temperatures and it's just as stable as H4350, but contains a decoppering agent, which is nice for extended shooting sessions. So far it's been H4350's equal in every load tried. The only occasions when there's been a difference in accuracy, 4451 has been slightly more accurate.
Started using RL-23 just last year, but so far am impressed as well. It's not quite as available as IMR4451, but far more so than H4350. Finally found some RL-16 this summer, but have only tried it in one cartridge so far, the 6.5 Creedmoor. It gets great velocity but so far accuracy hasn't been as good as with 4451.
