Man those pictures of the 3 horns could have come from our Corps. We have the same basic setup, but we have 2 Super Mags, a K-90 (still just 2 valve) and 2 smaller 2 valves (we only use one of these as we only have 4 players.)
Since I am not a Contra player I can't comment too much on long parades, but those Super Mags are HEAVY! They have an awesome sound, very full. Definitely a better sound then our small 2 Valvers.
Best way to find out about the condition of the Pioneer horns is too call them. They will be in the best position to tell you what the horns are like now.
If we had the money we would be buying more Super Mags but we just don't have that kind of cash right now.