Quick correction LoC, Phaeron is useless in warriors with the changes to RF.
That said, if possible, can you go 1x20 Warriors with an Ark, and do something else for troops? A 20 man blob is nigh invincible if it has its own ark and res orb. Its a big target that will soak up lots of fire and is hard to force a morale test on due to large numbers. Even if they can somehow manage to kill 5 models at the same time, or even over the course of the whole shooting phase, you will regenerate 2.5 warriors with RP and then an average of 2 with the Ark, meaning a regeneration of 4.5 warriors- Basically your opponent might as well have shot the dirt because he would have killed about the same amount of models. It presents an imposing advance and if you really like the steamroller feel of Necrons that they had in the days of 3rd and 4th, this will replicate that feel very nicely. I still have yet to be sold on Night Scythes over Doom Scythes- True, Doom Scythes eat a HS slot, but Night Scythes eat an all-important Dedicated Transport slot. If you plan to rely heavily on Immortals, maybe, but buying a Scythe for Warriors is, in my opinion, a bad move and a waste of what could have been an Ark. As it stands Doom Scythes are beyond deadly against anything that uses a lot of vehicles, able to outright destroy two or maybe more with luck with a single shooting phase- Including anything that might have skyfire. IG parking lots particularly lament their presence as do GK that just park a pair of Psyflemen in the back to shoot.
I'm off topic here, but to recap: Two units of 20 warriors is tough but can be whittled down. More importantly, having to large squads doubles the requirement of Res Orbs- And for the price of the Lord you are putting with the second squad plus the cost of the squad itself you could have bought an Ark and a smaller unit of Warriors to ride around in it and shoot out (Hooray open topped!) and have been much more effective. I'm also not sold on scythes, especially for warriors, so that makes option 2 more appealing to me. Honestly I would try to get one squad to 20 and reduce the other to whatever is left in points as they will spend the whole game riding in an AV13 F/S skimmer that will just veer off on turn 4/5 to drop them on an objective.