It does sound high (both the amount and the number affected), but not necessarily way off.
Nobody's pushing an uncapping, so it's not something I need to investigate right now. Plus I'm against it, tho not for the same reasons as Heritage. Don't forget benefits are capped too. To some extent political support for the program hinges on current limits to the degree of implied redistribution. Now isn't a great time to test those limits, but I would say to defend the basic concept of the program.
mbs