Bob,
I would be glad to go over the ASAE standards (universal rating system) of loader specifications that most loader companies follow.
It is how most companies standardize specs or take the measurments at the same PSI (hydraulic pressures) so you can compare lift capcities.
A third area that should also concern you is how the loader will fit or sit on the tractor. If it sits too far forward, you loose lift capacity. If it sits too high you can't see or you may not be able to "dig" with the loader.
If a company measures & publishes the lift capacity at the pivot point instead of the ASAE standard of 800mm out from the pivot point (bucket's front edge) you won't be able to lift what you thought you could.
When you talk about handling trees, adding a grapple, having stability... adding a ballast... there are many more items to consider to get you what you need to make your job easier.
Please call me at 877-MYLOADER and I'd be glad to give you pointers of what to look for in a quality built loader.
J. Ellingson