I have the TWL Digital American Series PCs for my integrated and SACD player. At the time of purchase, Cullen Cables didn't have the Crossover series and the most expensive cable line he had was about half the price of the TWL. I had that PC before getting the TWL.
The TWL were better than the Cullen Cable PC I had but I always wondered if the Crossover would have been good enough after they came out. The differences were there but they weren't huge and I think the Crossover would have narrowed the gap, if not equal it.
I still use the Cullen Cable PC for my Niagara 1200 with the TWL PCs still doing duty for the integrated and SACD player plugged into the Niagara and it all sounds great. There is no downside to this present set up. In fact, it's never sounded better.
I'd try the Cullen first and then go from there. Saving a thousand bucks is something to consider. If you really want to go with TWL, you can't go wrong with the Digital American series.
All the best,
Nonoise