So the major difference is the radiums are like the sun... Retina burning bright. I switched to an XM bulb for 2 weeks because I was literally burning my corals with the radium 10" above my tank.
The XM was a lot dimmer, slightly bluer, and that's when I said, "F it, I'm trying a real LED unit."
A whole back I tried a chinese LED light a friend loaned me, it was 12 royal blues, and 12 cool whites (claimed same power as a 250w halide). It was dim, and the corals told me to F off, because they didn't like it. Colors suffered, and I lost a blue acro. I guess the spectrum just wasn't there.
I can't say how that compares to a Sol Blue as I've never seen/used one, but I guess take it for what it's worth.
Let me know if my rambling didn't sufficiently answer.
Oh, and current FTS for the heck of it.