Yeah the bulkheads will always be a point of doubt. They haven't leaked so far and water has been in it for about three weeks now. I had a close inspection of the seals, which were thoroughly cleaned and checked, once installed. The two sealing ribs are concentric and free of debris on all of the bulkheads. There are still six points of failure(and another three in the weir) which as you've mentioned will be a right PITA to attend to should any of them fail - 700L sitting above them.
If I had my time again I don't think I'd go for holes in the bottom of the tank. Propeller pumps have progressed and the need for the closed loop has passed IMO. Here is my Reeflo Dart:



And the Oceans Motions:


OM is gone I think. That was the replacement motor, which I could only get in 110V too at great cost. Unless I can find something local I think it will be relegated to the priciest 5-way PVC plumbing to be found. Still undecided whether I replace the Dart. Maybe I can get the motor bearing kit and a new impeller but even the housing is in quite a sad state. I did have the thought to use one of the five CL returns and plumb it via the chiller. This would satisfy the desire for a redundancy to the main pump which was the reason for the tank crash. The con is that the CL would need to be run continuously whereas before I ran it in conjunction with lights-on plus a bit.
As for the eductors, well I think the claims were overstated but I've put them on again for now moreso for the ability to aim them but with the pump in pieces I've had to guess.
The rock was in tubs with LaCl for over a month and they got a few water changes in there too. I've put the rock in the display. Initially I was just going to throw it in and aquascape later but I found myself positioning them. Actually I thought I would be aquascaping dry and using cable ties and aquakneedit but it didn't happen and all the rock is stable but untethered, for now anyway. I did take pics but they are so badly affected by reflections they don't really show anything. I did get one from the end. The aquascaping ended up much like it was. In essence there are two bommies linked by a bridge. I think I did a good job of hiding the CL eductors and remebered to try to keep the height of the rock down. I don't think I went over three-rocks high and tried to keep more of the floor exposed which will eventually get sand, ie arognite or crushed marble.

The skimmer has been performing very well especially given it's supposed to be a near sterile tank ATM. This from under 24 hrs:

It is on the wet side but the skimmer keeps pulling this out. Although I used NSW at 1.027 I was about 150L short which is basically the sump running capacity. I reclaimed about 60L putting the rock in but SG sits at 1.021 for now. I'll get a bit more back when the S of the DSB is added again. Should see better skimmate again when the SG rises to normal.
You'll also see a temporary (semi-permanent perhaps) solution to reduce the spray in the cabinet - the styrene lid. Years and the thought never crossed my mind.
I have noticed that the water has yellowed. This is coming from the rock because I noticed the tub water was getting quite yellow but looked pretty clear towards the end of the time in the tubs after the last water change. I'll probably use carbon to try to clear it up. In my single days I think I'd just drop the airstone in and pump ozone with a window open but probably best not to do so with the kiddies and wifey hanging around all the time.
Tested the PO4 on the Hanna. After the tank was filled it was 0.02ppm. Yesterday it came in at 0.12ppm. I'll be sitting a jar of LaCl in the sump soon and see how that goes.