Don't lose sleep over it, LOL! You don't have to use all the cassetticons. 
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* But it would be cool! 

 

You could always use the Universe SE Overkill (the one only available through HTS). But then, he might be too big for your needs, especially if the others are all Scout class.

 

I'm certainly not keen on a Soundwave combiner, but I think it would be really cool to make a Soundwave Armada style. The cassettecons attaching to him like Minicons and boosting his power could certainly be cool, imo.

 

DO IT!    

 

It's a cool idea but with that many parts (8 for the limbs and 1-3 for the body) the stability would be of great consern not only would the gestalt have all it's own knee joints etc but the individual figs could still potentail twist and turn if not done right.

also who would you use for soundwave? the G1 is quite boxy and I don't think it would fit in with more modern molds.

however I still agree that the concept is great. however have you also thought about them simply becoming pieces of armour for soundwave? or combining without soundwave at all?

 

I was thinking TFU onslaught as SW. I am not concerned about stability either, this idea is just in "idea stage" i might jump into it when I find time in a few months.

 

I concur, I doubt stability will be an issue, that is something you engineer in while you're in the R&D stage.