I had both, iTunes and Sooloos. I must admit I had always thought the Sooloos is a waste of monies and an over priced music server. How wrong I was!
The iTunes stored in a 8TB NAS server (and also ripped DVD HD movies) while played thru the MacBook Pro does sound good by itself, but will be relegated to background music when compared to what Sooloos can do, especially thru the ID40 card of the 808.3.
To me, both can be operated using Apple's iPad2 or iPhone4, so operational convenience is on par. Its just the price viz performance factor that one would want to judge the "worth it" question between the two. Well, I started out with iTunes Lossless and now had both. The iTunes still served a purpose but more incline to movies than music, the later being the foundation library for me to burning a few CDs with songs of my choice for listening while I am driving. Serious musical enjoyment for me is now on Sooloos. If one had not played with Sooloos, then iTunes should suffice. However, this would take a complete change if Sooloos had entered one's life. Thats what happened to me!

Meridian 504FM, 808.3, 800v4 DAX, DSP8kSL, Sooloos C15 + Twinstores (3TB x 2).
Dr. Feickert Twin DFA Turntable, TriPlanar MkVII Tonearm,
Miyajima Shilabe Cartridge, Lehmann BC Decade Phono Stage.
Oppo BDP83se NuForce Edition. AKG K701 Headphones.
Shunyata Hydra Talos & Venom 3