I’m fine not having access to United F availability, because UA F is being phased out. I assume Polaris/J isn’t hard to get for M&M members and I’ve had no trouble booking LH J as a 1K.

The only Star carrier whose F I would be curious to try is SQ and they restrict availability. But as far as I know they started the practice.

I think it’s cool for premium cabins to be available across programs. But ultra premium/F award tickets should be available only to the airline’s elites, just as Star Golds shouldn’t have access to the FCL/FCT.

I’m obviously very biased. If airlines other than SQ and NH had comparable products I would be more flexible on this.