I much prefer T-VASIs to PAPIs, and I am not the slightest bit colour-blind.
For one thing, T-VASIs are pretty fool-proof and it's so bleeding obvious what they're getting at that. PAPIs, on the other hand, can be a bit hard to spot in terms of the colour changes (especially some of the cheapo dodgy installations that seem entirely consisting of suble pink than red or white, no matter whether you are high or low or on the glideslope).
There is also a danger in transitioning from T-VASI to PAPI unless the change is clearly brought to the pilot's attention (I know we should check, but still, anyway, there are those who don't, or plain forget!). "It's a T-VASI, so I'm on the right track. Oh DAMN! It's a PAPI and now I'm hopelessly high!!" can happen.
Anyway... I think PAPI is a backward step.
From the human factors perspective, T-VASI is far superior IMO.