The pump looks the same, power cords are the same length (16ft). The 6000 is definitely much cheaper and if you will run it as a 6000 for a good while it wouldn't be a bad way to go. Upgrading a 6000 to a 6100 requires a bigger transformer, they used big bulky copper coils instead of the laptop power supplies of the 6101. To upgrade costs about $80. The old coil I think is more durable than the laptop power supply but the laptop power supply can be had at any electronics store in a pinch and they are cheaper.