My instructor used to intentionally set the trims on the buddy box off a little bit. We'd get up in the air, he'd let me have control and ask "What's it doing? Does it need any trim changes?"

It definitely is something that needs to be learned otherwise you will be asking for the rest of your flying career for someone else to trim your plane for you after you make any kind of change.

I have a 9C but I bought it just before my 3rd plane was assembled. I used a computer radio before but it was the 6EAX so mixes and things like that were not as available. I love my 9C and the only thing it would have done for me at the beginning would have been to save me money up front. Now, at least I do have a backup radio if my 9C goes bad.

Really it's a personal choice on how much money you want to spend in my opinion but the bells and whistles won't start being useful until about the 3rd plane (if even then).