I had a similar though different experience with Elixirs. I play a lot of jazzy/bluesy stuff as you may have noticed, so I like having a slightly duller string tone to start with but what I did hear when I strung my strat with Elixirs for the first time was a magical sounding resonance to the strings. I can't describe the sound other than that.. they definitely sound different to every other brand of strings I have played.. almost to the point of you wondering whether there is something wrong with your guitar. I didn't have too much of the sustain issues you were talking about though.

So while I agree with you to some extent about the "dullness" they are definitely far from the dull sound you would hear on a 3 month old set of standard strings.. but yes I understand what you mean. I also agree with you that if you want that clean, bright tone that you would be better off buying the strings that are approximately half the price and changing them twice as often etc..

However.. if you are looking for some really great quality jazz-blues strings that will sound the same for 1 or 2 months (provided you keep them clean) or even longer if you're lucky, then Elixirs are definitely worth a try. Though they definitely sound different to "normal" strings as I commented about earlier.

EDIT: Oh yes.. I forgot about the slippery feeling.. yeh.. I don't like that either.. but then, I get the same slipperiness immediately after cleaning any strings.