Better? Yes. Way better? Probably not. I think the V is a 6 gang tuner and the I is a 5 gang tuner. Both of them are very good, but you would expect the V to be slightly better, as far as selectivity and sensitivity is concerned. As someone has already said, the Gamma I sounds similar to a Sansui TU-9900 and the Sansui is no slouch. I have never heard a Sansui TU-9900 so I'll take his word.
The Gamma V is a early digital tuner. It does lack some convienicies that later digital tuners have. It is kind of limited to only 6 presets. And if you unplug it, it'll lose those presets. If you just turn it off, those presets will remain. It also has a main power switch, along with an attenuator mounted on the back of it. I don't think it has a battery or supercap back up. The search function could also be a little bit more robust. But when you look past that and listen to it, I think you'll find it to be very excellent sounding and have excellent selectivity and sensitivity. They seem to be less common than the Gamma I, so finding one might take longer.
I think you would be happy with either one.