What features can't you use with the arduino?
Arduino has 56 IO pins on headers. The Seeduino has 70 IO pins, but costs 20 dollars more.. other than that they are the same.
Can't see why would it be so horrible to leave out a few IO pins in order to keep the board compatible with all the shields available. Do you really need all 70 IO pins?
I cant see why they(the official guys) did not want to, at least, bring those pins to an nonstandard headers !?!?!?
anyway when I started one of my current projects, I read the mega2560 doc and found it will fit nicely with all 6 timers/ counter ...
I wanted basically using 2 16 bits counters for external events (timer 4 and 5 external counter with hardware interrupt latching)
and 2 others for PWM , and others for the usual arduino stuff ( ms delay etc ..)
I was badly surprise to find that not all pins of timers were connected ...
So I told myself WTF are they doing!!!
And found that Seeed had build a correct board with all pin routed !
So for blinking leds the official board is fine , but not if you want to use all timers !
PS BTW one of my friend was not really lucky with the real cheap ebay version at $20 (board had crappy soldering on it)...
so paying a bit more (but still less than the official one) for a good board quality is not so bad !