Meganobz seem like a mixed bag to me. They are awesome looking units and I like the idea of them but they become such big targets that it is a bit of gamble. They are great in
CC with their powerklaws and 2+ armor but they can't gain invuln saves (unless you add Mad Dok
HQ for cybork), they cannot overwatch because of
SnP so they really need to get the charge, and they have problems with leadership since they cannot take a boss pole so you will need to stick them with a Warlord. If I were to use them I would probably stick 4-6 of them in a Battlewagon with a Big Mek w/
KFF + Boss Pole but keep in mind that if you have just one vehicle loaded with expensive units they will probably draw a lot of fire from the enemy.
The Mega nob models are also insanely expensive ($20+ for each one!!) but since you said you will be able to proxy I guess you don't have to worry about that. That being said, nothing is more glorious than a group of giant Orks in Mega Armor getting stuck in and wrecking people in propa' Orky fashion.
I feel like Orks are a bit better off going for a shooty list in 6th edition because of the
CC changes and overwatch. If I were you I would look into getting more Lootas and some Big Gunz or even a Dakkajet.. You can get a unit of 3 Kannons for only 60 points and they help with the Ork's lack of anti-armor.
You might also consider getting an Aegis Defense Line which is a pretty good point value
imo (100pts for Line + Quad Gun). They provide a 4+ cover save for your ranged units and a 2+ cover save
if they go to ground. Going to ground means you can only fire snap shots but this a big deal for Orks because they suck at shooting anyways. Hitting on 6's instead of 5's isn't so bad when you're dropping a mountain of dice from Lootas.
Either way, play what you like. Bring 200 Gretchin and a Weirdboy as long as you have fun doing it.
