How do you feel about the profile switching mechanic?

Will use it all the time.

This is the one thing I've got a real "meh" feeling about. It could work, I suppose, so I'm going to withhold judgement until I play the game.

I have no issue with it, I probably won't use it that much personally but it's nice having the option. And tbh I always found it stupid that a special forces soldier of Shepard's rank couldn't utilize certain abilities or use certain weapons cuz reasons, for example why couldn't soldier Shep use tactical cloak for instance? It's a tech power so it doesn't really require any inherent abilities like biotics, speaking of biotics the only logical explanation for Shepard being able to go from a soldier in ME1 to a Vanguard in ME2 is if Shepard has latent biotic abilities and simply chose not to use them and I imagine the same is true for the Ryder twins.

For Tech its not that he can't do it, its that it wouldn't fit some optimal state that Shepard would bring into crucial battle. That he has some limitations on what he can train into. Sure he could cloak, but he theoretically wouldn't even be as good with it as a classed Shepard would on even a single point skill. So he doesn't do it.

Not perfect, but I think that's the gist.

I'm not a huge fan of it; seems like a bit of a cop out to have all sorts of powers available shortly after switching profiles. It doesn't bother me tho, I'll most likely stick with 1 or 2 the whole time anyway.

I don't mind class, when they are well done.
But in Mass Effect you could only have one class at a time (something droped by a lot of RPG a long time ago) and  the limitation were weird.
Soldier had too few ability so he got ammunition ability but I don't see why another class couldn't use those ability.
I understand how having a drone require some tech dedication or the invisibility cloak being some kind of expensive prototype being given to a few individual that learns how to use it but it was disapointing. Adept not being able to use some biotic ability was a very arbritary restriction.

Kingdom of Amalur had a nice system.
For those who don't know it is very close to current ME:A.
You start with no class at all and you have 3 branch : Strength stuff, Dexterity stuff and Magic stuff. Each level we win some point in we can invest in those tree. Invest enough points in one tree or several and you get a profile with active and passive bonus. But the difference is that you each branch have tiers. Not only you have a stronger specialization by investing point in that profile but investing point in a branch unlock new tiers of ability.
ME:A is a "all you can eat menu" and that is good but it is overwhelming.

I don't think I need to have 12 active ability in ME:A. In the trilogy unless i played a biotic I do not need more than 4 abilities at all time. As a biotic having to change different profile to just access my other biotic ability is a break in the pace of the fight fortunatly using a power do no put everything on GCD anymore, playing biotic was a boring waiting game. But 3 abilities is not really optimal, it really need a 4th active slot. Most of my project build consist in one main profile and a secondary profile to access the 4th and 5th ability to complement my first profile. it is not to adapt to different situation but to answer the same one with more than 3 ability.
Fortunatly squadmate could be the solution, with their combo ability but it remains to be seen, I fear dumb AI once again.

3 profiles with 4 abilities would have been much better.

From a lore point of view im assuming the twins were all ready biotics, SAM it seems is the big red herring and is the key to this combat flexability, I assume sam is the reason we become pathfinder as well.

It depends on how they set it up within the story.

Could be cool, but only three powers at a time seems kinda too little... If the cooldown between profile switching is too long, it'll mean there's a whole lot more of shooting regardless of build, which I don't like.
Hopefully there's a more in-depth story reason for the mechanic than SAM (just my speculation)
But then again having charge and tactical cloak at the same sounds hilariously overpowered.

I'm not really sure.

I'm old school, I like defined classes in RPGs. I don't really like being able to do everything myself, especially in a game built around having a team with you.

I'll most likely focus on one or two profiles with each character I make and not spread the skills out too much.

So I guess the option is nice to have but I don't know how much I'll use it.

I love the idea of being able to change my fighting style in the same playthrought, I can use different style against different ennemies.