Does anyone have experience with tall wall bracing systems for ICF? I have used exensions (similar to those offered by Plumwall, Giraffe, etc.). This worked well but limits to approx 20' wall height. Any suggestions for systems capable of bracing walls 30'+?

Depends on how big the project is.
We have done a thirty two foot wall using wood I joists. It was not a long wall but was radiussed so we could not use standard scaffold.
If its a large project with straight walls, I would go with Nudura's tall wall system. Use standard bracing to do the first 10 feet and then put up two sections of scaffold and erect the next ten feet with standard bracing on top of the scaffold. Repeat.
Nudura has small hooks that are cast into the wall during the first pour. When you set up the scaffold, these hooks secure the scaffold to the already poured section of the wall. They also have brackets to adapt the strong back and brace to the top of the scaffold.

Have also heard that some use Zonts and Zuckles but I not sure I'd be comfortable with that.

I did a 24' 4 years ago. Poured the first 12' off of standard bracing then used standard scaffolding for the last shot with the regular bracing attached to the scaffolding. Not to keen about hanging by my fingers tips that far up. There is a company in Utah that has a rental system that looks good. It used to part of Arrx. Are you pouring all 30' in one pour? Uniscaffold is the name of the company in Idaho.

Thanks for the feedback! I am familiar with Nudura's system, but looking for other options - seems too labour intensive to erect scaffold, remove it, set up scaffolding, re-install bracing, and make sure not to forget/misplace the cast in wires, etc. It looks like a sturdy system that would work well, but I am hoping there is a better mouse trap available.

I don't want to look at Zonts for a tall wall.

Uniscaffold looks promising. If anyone has used this system, I would appreciate any positive/negative feedback.

Using scaffold is a great way. It can be more cost effective if shared by many trades. I've done a gym that the ICF contractor started with the scaffold and the carpenter/framer used it. It was last used by the stucco guy, who also removed it as he went. The building was 28' to truss bearing.