Imagine a drawing made in paint, then one in Photoshop. That's the difference. At least on the clean channels.
i watched plenty of reviews online as well, but I can't even begin to say what a difference it makes in real life.
The biggest difference you will hear, is like i mentioned on the clean channel. Not even debatable - it's way better than anything, except maybe the Blue Alnico (that, i feel has 5% better sound, but less Watts - so up to your priority).
Distortion is a different story - you may like the Vintage 30 sound (an excellent sound of course) or you may like the Gold Alnico, which is a detailed sound. even the fuzz is more HD, which creates the sensation of a very "clear" distortion. if you use 90% driven/high gain sounds, stick to the Vintage 30s or the similar ones from the G series, but if your repertoire is predominantly on cleans, or maybe you just care for a more HD sound, by all means, go for the Gold Alnico - the biggest change in sound you'll get for the money - right up there with upgrading your tubes.