On the topic of über-Raiders: they must have some pretty excellent STCs for those sponsons, I always thought a dedicated anti-tank turret on a Predator looked more impressive
Of course, Predator autocannons were bit scarier in WH40K 2E! Thank ye for the pages too, @Kyrt!
I actually quite like the simplicity of a system where you can say 'basic troops + (special rule)': it has a certain elegance that's very appealing. Representing all the Chaos Space Marine God-dedications and differentiating a few of the Eldar Aspects are probably the two poorest coverages, I guess (but even so, it seems like only Banshees or Dragons really miss out!).
If you did want more complexity, though, I think the way to go would be to modify things in the direction of EA: it would be easy to replace the E40K Close Combat with EA-style combat, allowing things like power swords to be represented as something different. Distinguishing between AP and AT firepower could be done quite easily too, whilst retaining the use of the Firepower chart method. E40K really is a remarkable engine for customisation!