I am sure that it will be the same as the first that being you can enter multiple trees without to much trouble. For example on torchlight 1 I made my ember mage a 2 handed fighter. So you should be able to do that skill set with ease.

There were some similar questions to Runic Matt/Jamus yesterday in the group chat. Just like they said, it is hard to answer, because themselves and few overall have played and can answer it.
But what they said and what I say is that all builds got weaknesses and strengths. It's a question about what difficulty you play, every single build may not work on Elite but alot does. I can imagine, having 2 weapon sets may give you advantages in some battles, and disadvantages in other battles. But that applies to all builds right?... Myself, I try to not be so strict with how I distribute my attribute stat points, always trying to adapt to how it turns out. Sometimes you might need to save 20 points before you know what you need.

In other words, do not worry if you play Normal, it will work out no matter what attributes you focus on. What I can suggest though is that you have one main weapon set, which you got passive skills for and stuff like that. The engineer has a passive skill in the 2h weapon skill tree that increases your attack speed, but this will not have any effect when you switch to 1h/shield... vice versa. That is just one example.
Another point is that you are probably capable of doing a more effective tank and DPS (at the same time) with either 2h or 1h/shield rather than mixing. Because you will be able to focus attributes more but mainly focusing your skills. This way you may pick skills that gives you regeneration of some sort and at the same time increasing your damage.

My own build will be an engineer with 2 weapon sets which one is the 1h/shield, building a tanky character. However, as my 2nd weapon set I got a cannon using long ranged attacks. My thoughts are that I now have the abillity to kite enemies and participate in battles even tho my health is very low. When the role as a tank can't be fulfilled anymore I will still be able to assist the team until I've recovered. Perhaps I'll put my best socketables for health/mana steal in my cannon, and try to make sure my cannon got regeneration stats rather than damage. Helping me to get back up in shape to dive into the fight again asap.

Finally my last suggestion is that you must not forget any attribute since none is useless to anyone now, you will need more mana and mana regeneration as an engineer, that's what I believe. Who would be better off with 10 more damage every normal attack instead of a bigger mana pool worth of 2 skill usages? =D