In terms of cut per impact, siege rhino is going to have the smallest effect since as a 3 color card it doesn't get played as often. If you want a different card in the Abzan slot sure, but I don't know if you need to consider aggro to make that decision.
I'm planning to replace it with some multicolored card from a completely different section (perhaps,
Domri, Anarch of Bolas to advertise Gruul Aggro better).
You're right, this replacement won't nerf Abzan that much, but a greater decrease in power (for now) doesn't seem to be needed anymore. I feel like we managed to achieve balance between the two decks by giving more spice to the aggro's mid-to-late game shell, where the problems mostly used to start.
I don't know how it behaves in people's environments, but in mine Scooze feels pretty safe (my playgroup confirms it), and Voice is even more gentle, in my opinion.
Kalitas and Liliana can for sure be called aggro-hating cards, but, to my mind, they're not that backbreaking when the aggro player has enough reach. However, I heard all of you, guys, and, as I said, I will keep watch... Where have I heard this phrase, though?
I feel like you can safely cut
plague engineer and not miss much.
When it works it's just a wildly under-priced
curse of death's hold and when it doesn't it's just grey ogre, so I'm not sure it's an effect you want in general.
Cut Engineer. Card's randomly a total dickhead.
It hasn't seen that much play yet, but I'm considering the cut. What could we play instead? I have several candidates:
Leaning towards my old pet card Fleshbag Marauder. I've been wanting to see how his staxing effect works in cube for a long time.
EDIT: I know there's also Woe Strider, but I'm already planning to replace Plague Belcher with it.
I'd also take a look at my ramp options if I were you. Your green section excels at ramping out some fat and locking aggro out. I had this problem in a past cube where green absolutely destroyed aggro because it was always hitting a t2 4/4 and/or t3 5/5.
All right, heard you, thanks. Though, Ramp hasn't appeared to be that badass yet. The most obnoxious scenario I've seen so far was t2
Courser of Kruphix against an aggro deck. But it general aggro in my cube seems to perfrom well against Ramp: last draft Rakdos Burn had a 2-1 win against Naya Ramp.