The original version of Hovel let you discard your hand to trash it. Apparently it was pretty much always the right decision to do it ASAP. This suggests that opening Great Hall to trash your Hovel is indeed a good idea.
Yea, I've been wondering about this statement a lot. My guess was that they simply misplayed it. I recall a bunch of games where you had the chance to trash hovel via great hall, but players rarely do it.
simulations show this:
silver/trash hits 5 with a 100.0% chance once and with a 0.0 % chance twice
silver/silver hits 5 with a 76.2995% chance once and with a 14.9157 % chance twice
which makes sense, silver/trash has 10 cards, so you'll draw all of them in your first 2 turns, and the hand with silver either hits 5$ or has both dead cards, in which case the next hand has 5 coppers and hits five, but you only have a total money of 9$, so you can't hit 5$ twice -> 100%/0%. one guaranteed 5$ is mostly preferable to the usual 76% one/15 two, so yea, maybe it' is better than i thought after all.