I am not the slightest bit interested in the difference between hearing the SAME thing live versus an online MP3.
I can only say that, after listening to CD's, and their equivalent MP3's (my iTunes collection) I am INTIMATELY aware of what the MP3 encoding process does to raw audio. One thing I can state without the slightest hesitation is that the encoding process has NEVER made anything that sounded great in the first place cease to sound great, and anything that sounded lousy as an MP3 didn't sound any major bit better when listened to as a CD..
In other words, if it sounds like crap on an MP3, it will NEVER sound like gold at full bandwidth. It will simply sound like slightly (very slightly!) better crap.
I am not talking about 128kbps encoded MP3's or lower. Those have long since been discounted as good quality (but the same principal applies - crap @ 128kbps never equated to gold at 44/16, just better quality crap) but 192kbps and higher (256 is my iTunes standard) is quite easy to confuse with the original, at least to the point of not altering something wonderful into something unlistenable.
But I still stand by my assertion that a stiff, poorly voiced, unnatural sounding internet demo would sound only a HAIR better in person. It would still be a stiff, poorly voiced, unnatural sounding LIVE piece of music. Not worth the drive...
I will be happy to drive to go and play a T3 in person (or a PA2Xpro), because the online demos have shown it to already be a quality sounding arranger. Until I hear a quality sounding OOTB demo from the MS or Wersi (I am NOT a 'home organ' music fan!) online, I am NOT going to drive any distance to hear those in person.
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An arranger is just a tool. What matters is what you build with it..!