|Shortening the commute to the battlefield|
When the new book came out it changed up the portal strategy a bit. Now you couldn't hold units for a late portal deployment, they made normal reserve rolls and the portal merely acted as a table edge. The plus side to this, is you gained a bit more flexibility in putting units where they needed to be. Infamously, this lead to bait and switch tactics where opponents would avoid the portal and push towards objectives in my backfield, only to have a unit come on from the board edge and take them out.
Now with 6th edition, I'm left wondering if someone really got mad at our portals. Reserves come much faster and more consistent so that portal has to be down turn 1, we can't get quite as deep into the opponents backfield with the new movement and disembark rules, and even if we do get the portal setup there is no more assaulting the turn we come in from reserves, and only half the army could be in reserve. On top of all those nerfs, the addition of Interceptor weapons mean even if we do manage to come in from the portal and expect to shoot, the major advantage is gone, we cannot avoid being shot at.
We are at that point now in 6th edition where people have begun to accept that the ally rules add such a great dimension to armies that there are any number of combinations that could produce unexpected results. As such I've seen more talk about trying to incorporate the webway portal in again. While I believe that I could work the portals in to have units of warriors, wracks, or jetbikes come out of the portal to shoot/turbo boost, the only real benefit I see to using the portal over putting them all in a Raider is that you could have more than 10 guys; i.e. 10 wracks and 3 haemonculi for 5 liquifiers. The only tactical option that comes to mind is to use the webway portals for board control, try and drop 2 or 3 of them at the mid-table range to cut the table in half. The problem being, how much will you have coming from reserve that will need 3 portals.
I really enjoy the webway portal, and will continue to see if I can work it into my army, but I think it has slowly lost all of it's benefits over time.