Given the strength of the hoe compared to my little tractor with the same 16" bucket, i would say focus on the ripper and skip the narrower buckets, for now anyway. No harm cutting a 16" hole if it isn't slowing you down much. The ripper will let you get through roots and pry up big rocks quite a bit faster. If you look at mine you can see it doesnt need to be complicated to work.
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Another thing im somewhat curious about.. BXpanded's ripper has '2 sides' or has features on both the front and the back. I have wondered how effective a single 'tooth' would be as a thumb, and right now im wondering if one couldn't make a thumb function so that the front was 'a thumb' and the back was more of a hook shaped ripper. It would be a bit odd in that you wouldn't be able to stab it down that far into a narrow hole because your bucket would still hit at some point, but that point would be ~22-24" on my machine and bigger on a bigger machine.. surely enough for most roots.. and if you could hook something with the backside of your 'thumb tooth' you could use multiple different hydraulic circuits to pull on it simultaneously.. hmm..