Does Chaos lead to power?
I am mostly talking about the Daemon Primarchs, but it can be asked about any chaos follower. I am of the opinion that chaos does not add to an individuals power, it just modifies what is already there. I look at it more like a drug. I don't think Angron gained anything when he 'ascended', he just started taking PCP. He did become stronger and more rabid by it, but what he gained in ferocity he lost in stability (what little he had left).
I don't think that Lorgar gained any power when he first turned. He was just able to use his existing latent powers better.
Argel Tal was more powerful, but that wasn't all him. A large amount of 'his' power came from Raum.
Do you think that Chaos gives any actual power to it's servants? To me it is like a drug and really adds nothing. If I got a head full of coke I might work for 3 days straight, feel great doing it... even get a promotion, but it hasn't 'given' me anything. What I gained in work and promotion it has taken away from me in health (among other things). With Chaos I think is very similar, except chaos takes more.