I have finally abandoned Augmented Engines and grabbed the four tugs (instead of sticking with two), and I can thank Ziggurat with Phase Anchor, partly because I only have one in the game and cannot build another. If I want Augmented Engines, I need to s-mod it in because of the two dock mod limit (I also want Efficiency Overhaul and Solar Shielding), but Phase Anchor puts a strain on the OP budget, and I need s-mods for various other hullmods (like Hardened Subsystems and ITU) Ziggurat needs to be overpowered and worth the 75 DP cost and other downsides.
Yes, four tugs instead of two hurt. 10 more DP toward Field Repairs, and less fleet slots for small ship spam and/or enemy ship recovery. But it is probably the lesser of the two costs. 40 OP for Augmented Engines is too expensive, and even s-modding it in may be a higher cost than lumping with two extra tugs.
It would be really nice to have a much cheaper +1 burn hullmod that does not alter other attributes that can impact DP pools for skills.