I think you have been mislead on speeds.
This is well worth a read;
Certainly a complex topic and that's a good link to try and understand it better
But that Iridium wifi product will be virtually useless - except if used very carefully by tech-savvy users.
One potential provider is ok to do a free test on the ground for me once I decide on what app or software to use, and then rent the kit for a day or a week to try it out before purchasing so one way or another I will come to a conclusion if a practical solution can be found.
I have a detailed writeup on my website on using sat phones to get wx data.
Thanks for that, you have certainly experimented with this extensively, for speed of finding here is the direct link to the well written topic.
Airborne Satellite Weather Data