I think the new mode won't be as varied or balanced as CTF was. A
few classes will probably tend to dominate in this new mode, and spirit regeneration will be practically irrelevant as I anticipate deaths will be frequent. Lighter, more mobility based classes are at a definite disadvantage on this map, but I hope they'll still be useful. I'll be very curious to see how Fengineers are used, and if they are useful, as it will be a lot harder to get set up, but potentially very rewarding. And there are lots of interesting places to try to set up a base.
The map will definitely succeed in making CTF playable by smaller numbers of people which is the main intent. It should also create more constant action, although you'll end up spending a lot more time spawning, you'll spend less time waiting for people to attack your flag, or running to grab a flag, and a lot more time smacking people with fish.
I still hope to finish my original plans, which use the same map, but a larger portion of it. It should support a more dynamic game and a little more strategy.
Edit: Another nice side effect of this new mode is I finished my plans to make the Team Fortress code generic. Now area helpers could contribute new maps with ease, for both game modes if they felt like it. So we might see far more areas than we could possibly need in the future. I'm probably moving all Team Fortress areas to the playground in Puddleby. They aren't getting much play on Thieves' Island, and probably don't fit there thematically.