While OP/cheating will always be personal opinion and an eternal debate, pneumatic engines *really* make RotaryCraft much easier. With it's ore multiplying system, that can drift into the realm of "OP" very quickly in my opinion.
Well, Modular power suite is OP, because you can rut and fly quickly, but apparently this is only one way to battle Nether with infernal mobs
Every and each mod is absolutely OP with respect to Vanilla, every technical mode is OP with respect to simple mods. So may be this is why we are so excited about new mod packs so we can enjoy this OP in one or another way!