Chemical powered booster: really, really, expensive.
This is the reason why nuclear propulsion was discarded. There is unfortunately no compelling (economic) reason for manned space travel, and the specialized robotic missions that NASA and similar agencies mount each cost a lot more than the cost of the expendable boosters used launch them.
If we built such a thing, and sent humans to visit Mars and begin to colonize the Moon, I would be thrilled. But it isn't going to happen in our lifetime.
Yes, your right the initial development is really, really expensive, but unlike most SSTO's this is truly reusable and it can save money simply by being used for nuclear waste disposal.
After all, how much are they spending to create that National Nuclear Waste Disposal site?