Wow, I leave this thread for 20 hours and there's a whole lot more. There are some great arguments for both sides. I'd agree with Fireblasto that we may need deployables but not necessarily the ones used in Tribes. Mines, while being a seemingly good idea for boobytrapping routes to the base, in a game with jetpacks, the mines are easy to get over without detonation. Also, turrets would hamper the balance of the game. Generators may be a good idea, but adding too many facets to base defense will leave everybody wanting to go on offense in PUBs and leave the game to go by quickly, or in clan competitions or in PUGs, while there would be few defenders needed for a more brutal offense, those few players would suddenly be overwhelmed by the offense and once the generator goes down, there wouldn't be enough defensive power to hold off the onslaught while the generator is being repaired. I could see much more frustration from all sides coming up from a turret/generator combo to aid in base defense.
Sensors, or some other method of spying on the enemy base or cap routes, on the other hand, I think is a great idea. The sensors could be set up on cap routes so that the defense knows which way the next invader is coming from, or for chasers to know which way the flag went (though if the flag is always on the HUD, that may not be the greatest priority.) Obtaining tactical knowledge is important for defense and cappers moreso than the others. If the cappers can look through a spycam and see if their approach is good moments before they execute it, then they can use that information to make a decision before they actually go in.
Turrets (possibly the tetchiest subject on this thread) is something I disagree with. The turrets would, in order to be effective, have a huge radius of awareness, and then create this large circle of body parts around the base. Deployable turrets could be set up on cap routes, and while that may encourage people to think about new routes, there would need to be a limit on how many turrets could be placed by each team or else turrets would dominate the landscape and nobody would be able to get past a no-man's land.
Capturable mid-point bases: I like this idea, the maps would have to be huge, and how many would there be on each map? There could be many, and then a game similar to Onslaught from Unreal Tournament or Capture Point from TF2 could be produced from this, but with the legions touch. Advantages to having a capturable base in a game of epic CTF would include a closer spawn point for offensive players and desperate chasers, but not a capping zone in that base. I could see there being one midpoint base for a very long and thin map, which doesn't sound like fun, but if there was a map that was huge, then there could be bases scattered throughout. They don't all need to be large, either. Some could be like those tiny buildings in Blade Run that are out by the perimeter. Also, by huge maps, I mean something significantly larger than Blade Run.