Why no plasma calibers

As for each unit:
If you're taking a full squad why not take all 3 special weapons? Can't have data tether AND omnispex it is one or the other. Not sure power swords are worth it on guys that never want to be in combat.
I'm not super convinced on the Dunewalkers. Yes 3 S10 Ap1 blasts is good, but that is 345 points that has to shoot at 1 target a turn. Are 3 Dunewalkers really nearly as good as a Knight?
Whilst the
AA version you have only has the 5++ and is 250 points that does nothing if your opponent doesn't have any flyers, FMVs or skimmers (e.g. Adlance, most Imperial lists, Tau, Necron ~ as their skimmers are AV13 so largely immune to the Onager,
CSMs, Orks). Can you afford to be 250 points down against those armies?