Yeah rumble/vibration sucks, it is as much fun and useful as holding a powersander all day.
For that reason I turn it off or on a very low setting in most games.

I agree that the D-pad of my Logi sucks, but then again I don't saw any use of it anyway. The XBox360 has a decent D-Pad, but still I don't use it much.

Never realised that. I knew the face buttons were pressure sensitive - it has been like that since the PS2 and that really pissed me off in games like Gran Turismo 4. Are there any games that support the pressure-sensitive D-pad? I don't have any...

I found it in MGS4, where the d-pad is used to pan and zoom camera in the cutscenes when you're bored.

Just a small, shameless bump.

I've found an F510 in a brazillian online store, the last one in fact. While it was still more expensive than buying another Xbox controller, I think it might be useful as a Direct-Input gamepad plus extra X-Input controller for local co-op. I'm still not sure, though, so I'd like to ask a couple of questions.

1 - Do you guys prefer concave or convex thumbsticks? I'm used to the concave sticks in the Xbox controller, but I hadn't used a gamepad since Master System 3 (which didn't have sticks, by the way).

2 - Can anyone compare the vibration in the F510 vs the Xbox Controller? I actually like it, though I think I won't mind if it's a little weaker.

3 - Suppose I'm not really interested in playing co-op with controllers. Considering I already have an Xbox controller, would the Logitech still be worth it, or would I be better looking for some cheaper D-Input only pad?

My brother has a spare, cheap d-input controller I'm going to check out, but I think it's probably too low quality. Still, I hope I can get some answers before the package arrives and I open it. It's pretty expensive and I would feel better returning it to the store unopened, if I do return it.

Depends on the surface. If it's rubber-coated, convex tends to be better. If it's a cheapie plastic one, then concave is better.

The F510 feels a little stronger to me, although that may be because it's smaller than the 360 pad.

There are quite a few D-input games that will not produce force feedback on a 360 gamepad without using the custom drivers, and the two analogue triggers serve as a single axes for DirectInput games, which some older games tend to hate with a vengeance. In games like GTA 3, you won't be able to assign them to anything in XInput mode.

Thanks for the answers. It seems you didn't get this last question, though. What I'm asking is, suppose I don't need another X-Input pad. Are there cheaper, but still quality D-Input-only alternatives to the F510?

What you said, I found out the hard way a few months ago -_-