I too am in favour of extra work on vocabulary. I was aware when we first began a CM style education that simply talking about new vocab words when they come up in readings was more “the way it’s done”, but my ds10 and ds8 seemed to zone out a bit on these discussions…so I decided to try a workbook format – Wordly Wise – about a year ago. For ds 10 (5th grade) it has gone quite well, though I wouldn’t say it’s completely independent (of course, this may have just been my kid). There are some exercises that tie in bits of grammar, so on those days I would sit and work with him. There are other times where WW really challenges you on the word meanings; in those instances we work together because unless my ds10 is really in the mood to concentrate and work diligently, the WW workbook format makes it easy to just give up, pick an answer and move on. Of course, when that happens (when child is working independently) we just do a little chat/corrections session after he’s done. Having said all this, perhaps the other workbook you are looking at Vocab from the Classical Roots wouldn’t allow for this (?) if the workbook had different formats to the questions.
For ds8, it has not gone quite as well, he was probably a bit young to begin (even though I started him at a lower level).
For what it’s worth, when I was at a homeschool conference this past Spring I had a fascinating chat with young lady who had recently completed her first year of college (she was helping out at a booth). I was browsing the Wordly Wise section and she offered to help me, and as we talked I got a great story from her on how she really felt Wordly had helped her with her SATs and how she truly felt that out of all the curriculum during her homeschool years, WW is among “the” ones she feels is being put to good use. (and I really don’t think it was a sales pitch, LOL).
In short – I guess, like all curricula, there will be variation on what works/what doesn’t, based on the child. Hope this helps a bit! Angie