I actually only found out about those ones this year. I can't believe I never saw them in store.
Printable View
They did shelfwarm for quite a long time, despite their awesomeness. I suspect that the problem may have been that Hasbro took too long to release them, i.e. by time they came out, the ROTF hype had fizzled down. They had a TRU exclusive all green repaint of this set too, that also shelf warmed.
Ah damn that's not fair! The only TRU I get to regularly are Highpoint and occasionally Northland. Both of them seem to magically run out of stock after months and months and months of gathering dust, just because I decide 'stuff it I'll pay the full price'. I'm sure Universe Predacon and Stormcloud (or Dreadwing--one of the Ultras) sat on the shelves for about 15 months, no clearances, no sales. Nothing. Just a thick layer of dust. Until I wanted them.
It's still about 6 months away, but the teaser images for Metroplex are now being released... showing off how tall it will be compared to the just-released Fortress Maximus.
Metroplex may be taller, but he won't be the biggest... by sheer volume and weight, I think that title will stay with Fort Max.