First off, there's pictures of the 3 VM TV boxes here - the TiVo & V6 both run TiVo software, the V6 & 360 are the same physical box hardware but 360 runs completely different software platform.
With that in mind - forget everything you know about TiVo and consider 360 as completely different. The user interface is different - clearly newer. While both boxes are "recording set top boxes" with access to VM's OnDemand services, the way they go about things is different.
360 has some newer functions such as recording profiles & voice control, but does a few other things differently. Some TiVo-functionality such as series-linking, is a lot simpler in 360 and doesn't currently offer as many variables & tweaks. There's been a few previous threads comparing features and whether the 360 is better or worse than your V6 for you does significantly depend on how you use your box and whether there's any specific features of your V6 you like - and check if the 360 has them, or does that function differently.
A conversion to 360 can't be reverted, so you can't try it out first.
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