yes yes yes, true tides are even more devastating than mostly tides.
Put simply, if you can be bothered with longer games due to model movement alone then yes, and they are awesomely powerful lists.
As an interest point, i played both of my green tide armies this weekend (in 1500)
Both lists here:
http://www.heresy-online.net/forums/showthread.php?t=66150
They rocked the socks off everyone they came up against, Including a basilisk heavy IG army. They just could not get enough shots off to kill 180 orks. It was a sight to behold.
The biggest problem I have found is deployment. I almost didn't have enough room for them on the table. I would suggest though, at a tournament, people would have a hard time facing you.
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Additional: There are 2 ways to run a green tide.
1. Kan wall,, full army + 9 Kanz with rokkits or grotzookaz
2. full tide, like the lists above.
Unfortunately no other way (I have seen, or played with) works on a largely competitive level