This is a great question and something I've thought about from the opposite point of view.
I started as an old-fashioned orchestrator/player when there was no such thing as a sampler. I learned the most basic way possible - by playing in the same bands and orchestras that played my music. So I had the experience - sometimes disturbing - of hearing things I wrote played by both mediocre and good players, and that made me try to write things that were "solid" - in other words, practical to play, suited to the technique of the instrument, etc. so that it would sound o.k. even if the orchestra wasn't so great.
That's probably the main advantage with learning the traditional way - you will be more aware of problems you create in your use of the instruments.
However, this is something that startled me when I started using samples that were really good - Miraslav and others and then the VSL - everything you do in orchestrating with samples is applicable to live orchestras. It is a tremendous tool not only for recording music, but for learning about orchestration. Also, I've had the same pieces played by samples and live orchestras, and though this contradicts Paul somewhat, I've found it is not true that the live always sounds better. If you have the New York Philharmonic, it probably will. But if you have the Gardnerville Symphony or the Peyoche Chamber Players - don't count on it.
I started as an old-fashioned orchestrator/player when there was no such thing as a sampler. I learned the most basic way possible - by playing in the same bands and orchestras that played my music. So I had the experience - sometimes disturbing - of hearing things I wrote played by both mediocre and good players, and that made me try to write things that were "solid" - in other words, practical to play, suited to the technique of the instrument, etc. so that it would sound o.k. even if the orchestra wasn't so great.
That's probably the main advantage with learning the traditional way - you will be more aware of problems you create in your use of the instruments.
However, this is something that startled me when I started using samples that were really good - Miraslav and others and then the VSL - everything you do in orchestrating with samples is applicable to live orchestras. It is a tremendous tool not only for recording music, but for learning about orchestration. Also, I've had the same pieces played by samples and live orchestras, and though this contradicts Paul somewhat, I've found it is not true that the live always sounds better. If you have the New York Philharmonic, it probably will. But if you have the Gardnerville Symphony or the Peyoche Chamber Players - don't count on it.