I was looking at buying another sedan recently and I read and asked some questions about both cars.
I found the X-ray to be the most appealing, but the cost and lack of parts availablity is why I didn't choose it. Its not that the price of the car isn't worth it, but its one the most expensive sedans on the market.
The xxxs seems like a really great car and for the me the parts availability is also good. But like other have mentioned before it comes with zero hop-ups, and to buy all the hop-ups would end up costing at least a few hundred dollars. These hop-ups like ti- turnbuckles, graphite stuff, thread shocks, etc already come on most other high end kits(ft tc3, MR4TCSp, X-ray) for much cheaper.
If you can get parts for both the Xray may be a better choice. I wouldn't consider the xxxs until Losi comes out with a special edtion kit like the Kinwald or Francis edtion with all the goodies included.