I find the embrace of the spider to be a little better than the sundial as well - Someone else did the math, but given that haste scales better than crit for pretty much every warlock spec according to the spreadsheet I'm pretty sure thats right. Its a pretty minor difference overall though, but I do like that the spellpower portion of the sider is a constant instead of a proc.
yesterday my connectiong was finally running so i tried Dying + Embrace, and i can tell that was awsome; when the embrace procced i had like 1100 haste, and that was kinda fun.
this evening i'm gonna try Extract + Embrace
PS - Thanks Weerea, i wrote the wrong trinket name, yesterday i was using Dying + Embrace ;-)