You can certainly use that (though static list is more preferable), but I suspect one other thing here : Nesting of smart lists (Using "Member of Smart List" <smart_list_name> inside the Smart List of your Campaigns) here would increase the processing time of your campaigns, what marketo recommends is using a segmentation instead of going for a nested smart list to improve the system performance. Also a segmentation would be much cleaner way to maintain than a smart list IMO. Just a suggestion to think upon!
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