Well the advantage of sight readers is how they manage to fake it without messing it up.hehe
That's one thing I've noticed except lang if they are reading a piece of a classical music which is specific. One thing I've noticed sa mga informally trained fellows is they have a good ear but when communicating with other peeps like the formally trained one,they don't know the terms.
I know people who can really sight read on the spot, but it took a lot of practice as well.
It depends on the instrument also.
I salute the senyor of the scene formally or informally trained,for me it's about experience and making the music feel good,make it swing or whatever it is. You should have heart for this as well,not just reading or playing music technically. Like blues it takes a big deal of feel to it,it's not inborn,hehe.It's not about where did you study or who taught you or you a have a long line of experience.
Anyway aral ako,one advantage is studying books on my own but experience still brings a big factor on your playing.