This is not so much an upgrade as a complete change of TV box software, fundamentally TV360 is not TiVo in the same way as Android is not Apple. Your series links and recordings are completely wiped as part of the hard drive being reformatted to convert.
Whether it's worth doing is a choice only you can make, but you should be aware there are substantial differences between the TiVo-software that your V6 runs, and the Horizon-software that would be installed in its place. There are pros & cons both ways, which you'd do well to research past threads on here.
That way, you can choose whether to convert or not, on an informed basis.