I'm not really an authority but I am an affliction lock, so, if you want any more input... here's my 2 cents

I wouldn't bother with cataclysm really. I'd probably take that 1 extra point and put it into Shadowburn personally

Not much use on bosses but great for 1- or 2- mob trash pulls for that extra bit of dps at the end. Afflic locks are painfully short on ranged instants. Between haunt and demon armor you're getting enough self healing that an extra life tap here and there won't do any harm. Worse comes to worst, you can always death coil

so mana's not a big issue imo.
I have 2/2 improved drain soul as well instead of amplify curse... I find I have troubles with threat sometimes as is, so I don't want to risk 10% extra threat.
I have one point each in grim reach and destructive reach just because of how motile many of the fights are. You'd be amazed how much easier it is just having those few extra yards to work with.
I also have 3/3 eradication. Most of the time you're casting non-instant spells (UA, Haunt, Shadowbolt) so it's surprisingly useful.
Other than that I think the specs are the same ^^