Hi Fox.
Major Concerns
The map feels very long. As a heavy my primary concern, aside from keeping my opponent in the circle until they fall over is the length of time it takes to get from point A to point B. Your map stretches these distances out in many cases. The rooms where the points are very big, both vertically and horizontally. On top of that the transition paths between the points are also very long. Between the final point and the second point you have multiple hallways as well as the attack space of the final point itself. Think of Granary. The distance between the 2nd and final point coming into view is maybe 1000 units, give or take. Give some serious thought to how you can adjust the distances between the major locations, if not the major locations themselves. Sometimes less is more.
Center
The center point has a good bit of height variety to it, but I would suggest halving the difference between the height of the point and the height of the waterway around it, or failing that raise up a bit of the ground to the sides where you currently have the ramps leading up to the point and then ramp down to the rest of the ground from there. I would also suggest widening the placement of the entry points and providing more cover for them and less for the point itself. This might improve the contest for it as anyone attempting to it will be more exposed, while both attackers and defenders will have more support from the geometry upon entering the area.
Second
The route to the second point could be the right size but the scale and separation of the paths feels too great. Consider tightening them up. The point itself is very claustrophobic and the attacking team doesn't have a lot of options. The circular frame above the point is as good an example as any to start on this next issue, the feel of the map is schizophrenic. On one hand you have natural rock and on the other you were talking about throwing spy tech computers into it. Pick one and define the location with it rather than trying to mix them.
Final
The final point is problematic. the area around it is simultaneously too large and too cramped. The paths the player moves down are very long with little cover. The big wall just in front of the point runs right up to it allowing attackers in without defenders seeing them until the last second. The route to the left is also, similarly right on top of the point. Those upper bridges don't do the defenders any favors either seeing as the access point for them is pointed straight at the attackers. Once again think of Granary, it's final point is wide open, and while the attackers have no less then four ways into the room, the defending team has it's back against a wall along with powerful sight lines.
Similarly to point two your choice of architecture for the final point feels like it's all over the place. You mentioned that the spillway, when not in use, is used as storage. I'm not even going to start on how ridiculous that is. Instead I'm going to suggest that you rebuild it to suit it's purpose better. Rounded half pipes leading away from where the water lands. Suspend the point over a pit or a deeper pool of water. Make all the walkways for the defending team elevated by 128 or so above the main path and make all the non elevated path ways piping or something similar. Maybe the route from the final point to the second point is a series of three parallel pipes cutting through a rock wall, angled down from the spill way to ground level on the next point. Maybe those pipes are no more then 500 or so units long. Maybe they exit out right on top of the 2nd point, fulfilling my earlier suggestion of reducing the distance between locations.