I loaded up two sets of 10 7mm Rem with 150 TTSX and H1000 for ladder testing today. The Barnes Manual lists max charge as 68gr. This evening I pulled up Hodgdon's data and they're saying 73.8gr for a max... Seems like a big difference, almost 6gr.

Wish I had looked at both beforehand - I might have taken a different approach. Which is more trustworthy?

Since both are not only equally trustworthy but also correct, it would seem that the only prudent course of action would be to purchase whatever piece of equipment was used by one of them (your choice) and use it for your shooting/hunting.

A chronograph will tell you which is correct

You are best to err on the side of caution, after all, it's your rifle.
Had a similar situation with a rifle in a new (at the time) caliber. Was using Barnes bullets but they had no data so used the data out of the Hornady manual because they did have data for the cartridge. When the next Barnes manual came out my load was 3gr above the Barnes max load. It shot fine in my rifle so I continued to use it.
A chronograph will tell the story.

Ask your rifle.
Start low and work up.
Watch your Chrony, watch your pressure signs.

Stop when your rifle says stop.