There's a lot to say. Boarding mechanics are way better in the beta but I don't think they are good enough or satisfactory.
Let's address the elephant in the room : call to arms
Giving the boarded player a way to fight back is a good idea, but most of the time using it is not one. In my experience it breaks down to two situations.
- The first, and the good one, you have a chance too fight back in close range the "boarding army". In this case I feel CTA does the job. The boading guys uses his ressources to put enough stacks on your ships. As the receiving player you can delay or ignore. If you ignore your ships retain their efficiency but will be severly criple or hulked later and if you want to use it the boarding player get a immediate effect on the fight with CTA malus. But in my experience this situation is not so common.
- Most often races with threatening boarding options are stronger thant the opposing force in close range. (due to boarding alone or strong close range dps) in this situation the other player will try to kit / avoid / disengage from the fight. In that case he just can not use CTA, because the ship will be unable to keep the distance and will get wreck alone. And if you d'ont use it your ships get hulked or a destroyed engine one minute later. It's very obvious with Eldars, but a IN, TAU or Chaos player trying to kit nids for example has the same problem.
Another issue with CTA, the malus to boarding damage is a fix amount. So it's ridiulously op against average troop efficiency. You pretty negate all the damage. And useless againt very good and higher (sm / nids) because stacks do a lot of damage and/or there's plenty of critical damages.
Same with recrew. One troop doesn't change anything, you can't even recrew hulk reliabily since most of the time you will loose it to random damages. You're not even forcing the boarding player to use one more boarding action this way. It should be at least 2 troops for LC and more for heavier ships.
EDIT : I find that in the beta escort get hulked to quickly, you can't do anything it's too easy for sm escorts to destroy opposing escorts.
Now my opinion in general about boarding. Right now you have two seperate gameplay mechanics to "destroy" a ship. You can damage or hulk it. You wanted to give brawling armys another option. But it's doesn't feel right, for me at least. SM don't have "another option" they suck at everything else. They just have to rely en boarding. That's not "more options". But you can't really give them good damage because if they are good at both it will be over the top. Same problem with nids, crapy dps / mobility / fighters but excellent boarding. (let's ignore the beta :D) In the other hand if your boarding capicity is not good enough you can just as well ignore it totaly since it doesn't help you damage and destroy ships anyway.
Since both mechanics are independant they have to be good enough in their own and you can't be good at both. So to "give more options" you should become good at boarding only with some types of ships or some upgrades. That way you really could choose between two options. Do I get this awesome battlebarge full of guns or do I take this one with amazing assault?
Another solution would be to have boarding as a support for damage instead as an alternative. Boarding could give you reliable strong debuff / critical damages / dot (fire / breach). That way a low damage army like SM could compensate by cripling / debuffing / lowering moral. And races with average or worst troop efficiency would have a incentive to do even a little boarding to have some crit/fire as a little plus.
EDIT 2 : I forgot to say that boarding torps having infinite range feels cheesy. And I have the impression that sometimes torps are not always drawn and you get boarded by invisible ones.