The problem is, if you read the reviews on these Sylvanias, these higher-performing bulbs don't seem to last long. Plus, if they have more blue coloring (like the ZXEs), they output less light.
As for the Philips having "slightly brighter" light, I suppose I'd be OK with that. I'm not sure I need a
lot more output. I suspect that the SS Ultras would be similar.
For an HID look, I wonder how the ZXEs compare in output?
I wouldn't want dimmer than stock just for the "look". Tempting, though.
I don't think you're going to get a lot more output unless you go to non-street legal bulbs like the 65w ones or some sort of retrofit.