Here are my considerations, please chime in with your own. I love the way 1400's sound but I'm not crazy about the way they look (is anyone?) and have owned L300's off and on for several years. I can buy a pair of 1400's for what I can get for my pristine 300's, so assume money is not an issue. I sold my first pair of 300's a few years ago and wasn't happy until scoring my present pair.
L300 Pluses:
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> I think they look extremely cool
> The lowboy style is very practical and doesn't dominate a room like most large speakers
> They sound great
> I already own them
> Resale value continues to climb and they're in demand
L300 Minuses:
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> Dated technology
> More "colored" than the 1400's
1400 Array Pluses:
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> I think they sound quite a bit better than the 300's
1400 Array Minuses:
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> Ugly
> Level or falling resale value
> If I don't like them in my room I will have a tough time selling them, and an even tougher time finding another pair of L300s as nice as my current pair
Right now I'm leaning towards making the move but would be curious to hear from others familiar with both speakers. Owning both at the same time and deciding which I like best is not an option unfortunately.