i had the same problem on two falcons, first one boots xell really fast, but it won't boot into the hacked dash at all.
the second one boots xell ok, and it booted into dash 2 or 3 times, but that's it. reflashed the nand with the ecc image, boots xell, wrote the dash image again, no luck.
i gave up and restored both of them to the stock image. rgh 2.0 is really crappy, and doesn't work at all as intended. tried all kinds of settings, used the coaxial cable supplied with the CR rev C, my soldering is spot on.
i've had about 30-40 phats with 14719 and updated cb's, and only 5 or 6 could actually be usable with the rgh installed. from now on i'm not doing rgh 2.0 anymore, till they fix it. it's just wasted time.