Just to make sure we're talking about the same item, here's what I got:
http://cgi.ebay.com/iPod-UNIVERSAL-...20336QQcmdZViewItemQQ_trksidZp1713.m153.l1262
I'm pretty convinced that it's an original Apple item: very solid, excellent fit/finish, branding on packaging and item look legit. So it must be an old iPod dock, just not a Universal Dock (as it is advertised).
Advantages (of this dock over 3G dock):
1. Cheaper (I got two of them for $34 shipped, two OEM 3G docks would be $60+).
2. Less likely to cause scratching of the bottom of the iPhone, as the only part that comes into contact with anything (when properly placed) is the actual male/female charger connection.
3. Better balanced than the 3G dock (there is a part of the dock that protrudes forward, so that it is less likely to fall forward).
Disadvantages (of this dock compared to 3G dock):
1. Because the Universal Dock adapter does not fit, I'm worried about the male/female charger connection being the only thing holding the iPhone to the charger. It's pretty stable, but I feel that if I pushed it forward or back inadvertently I might do damage to the connector(s).
2. Home button a bit difficult to press (slightly obscured compared to 3G dock).
So, I can't really tell you what you should do but keep the above in mind. I'm still kind of torn. These come from Hong Kong, so return shipping (which the seller refuses to pay, despite the 'false' advertising which he has not yet corrected) will cost me $13+. Actually, if given the above +/- you'd be interested in these for $34 shipped, I'd do it (because, assuming you're in the US, it would be cheaper for me to ship to you than back to HK).