LSis were good speakers but they really failed to deliver quality midrange deserving of the price category they were after. The LSiMs have improved there. I'd probably take the NHTs over the LSis.
Of course it has to be looked at in terms of the whole use case, but in general, LSis were short lived because the people buying them just for the Polk name more often than not destroyed them because they tried to hook them up to a typical receiver and then proceed to try to drive them at elevated levels. That equaled fried tweeters and the vifa tweeters were probably the most expensive component in there.