The 9-beam SB that Iso-T used succesfully against Mentar in DH3 was something we discussed in the Helsinki meeting in April where I argued it is always better than the 10-beam version when fighting carriers one-on-one. At the time I could not recall the exact configuration to support my claim, but afterwards I dug into my notes and did some simulations. It turned out there are situations where 9-beams are worse than 10, but in general I'd still argue that 60/0/270 (fighters/SB defense/Planetary Defense) is the best config to fight against carriers.
See below how certain ships (HP + full fighter load) fare against three types of SBs:
1. 60/0/270 (the best 9-beam SB)
2. 60/200/366 (10M max pop)
3. 60/200/382 (11M overpopulated planet)
Bio
53-47, 65-35, 63-37
Fed Bio
59-41, 71-29, 69-31
Virgo
45-55, 46-54, 43-57
Fed Virgo
56-44, 62-38, 60-40
Golem
32-68, 34-66, 34-66
Fed Golem
53-47, 48-52, 48-52
The same idea applies to low population worlds, where increasing the beam count from 9 to 10 actually decreases SB’s chances to win. The same ships fighting against the following two SBs:
1. 60/200/70
2. 60/200/71
Bio
74-26, 84-16
Fed Bio
80-20, 86-14
Virgo
70-30, 82-18
Fed Virgo
76-24, 80-20
Golem
36-64, 40-60
Fed Golem
59-41, 68-32