Sounds like an absolutely ripping idea to me !!
Pro-Ject have a an established reputation for good quality gear at an affordable price and their TTs generally get good reviews by critics and users alike so the idea of adding an AD converter to the existing options is a real winner.
I have been digitising my vinyl for yonks and have used a number of gizmos; orginally from the likes of Roland/Edirol and Bheringer and more recently M-Audio and now Focusrite.
The Focusrite mixer I use at the moment has the option of outputting the digital conversion via a Coax SPDIF and I have quite often used that for listening while ripping - the sound is only marginally inferior to the original analogue source and I could quite happily live with it.
Only problem with my way of doing things over the Pro-Ject solution is the additional expense of an AD converter and phono stage - the only downside of their TT that I can see is a loss of flexibility in the choice of these two.
Obviously for obsessed 'box-swappers' this would be a huge deal breaker but if I was in the market for a new TT, I would definitely give the Pro-Ject a go (and have some fun)