You are right indeed. I was a bit fast with my answer and did not take into account the following fact.
RadComboBox renders a <li> element for each Item even if it has a Template (and the approach I suggested to you will not work). In this sense having a <table> for each element will be inevitable unless you use some other element, <div> for example. In any case, many <table>s are worse than many other elements performance-wise.
Please excuse me for misleading you and let me know if you have additional questions.
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