I'd say check out the Ibanez 7-stringers. The muddy sound could have just been crappy pups on that LTD. I've found that it's almost impossible to judge a trem-equipped guitar in the store because they're rarely given much setup and then players molest them further.
I had a Carvin 7 string and it was great. It had nice clear tone all the way down to the low B (though I usually tuned it to A). If you're just looking for lower notes you aren't using an extended range guitar to it's full potential. A seven string allows you to play chord forms you wouldn't be able to play on a regular guitar and you don't need to change positions as often when you are playing licks or patterns. Here's a pick of the Carvin (I stupidly sold it three years ago).