I have a template with over 1,000 tracks (my articulations aren't keyswitched, on purpose), by using VEP to host the instruments. If you're going to do large orchestral work anyway, VEP or Bidule is a must (though Bidule is far more complex and VEP is a bit more automatic about the LAN stuff if you're using more than one computer to host instruments). Studio One handles my template just fine. Spitfire, VSL, 8dio, I run a lot.
The only drawback is video. Studio One is behind the curve there. That said, it will catch up soon enough and when it does, Cubase won't stand a chance in the long term cause Studio One is a dream come true in every other respect. I used Cubase from v5 until last year. Years and years of pain points.