well, amnesia level 5 is one of the worst things if done wrong. I tried what you are planning a while back and got mixed feedback for my approach on letting them know who and what they are and can do. Obviously the cyberware and gear they have can give them clues.
We had the most fun when the mage realized what he was AFTER he had cast his fifth spell... I could pick up on the characters emotions (luckily he was a good role-player) and let him cast spells according to them and give him illusions about his totem. With the others it was harder, for example they had one car between them and untill they had figured out whose it was (no rigger in the group) it was on S damage.
Generally it is easier to figure out what the character can do the more they are focussed on combat. Faces need lots of role-playing and hints from the other characters or npcs ("dude, you totally convinced me, i'm glad you didn't want me to dance naked on the street'). im glad we didnt have a decker on the team, i dont know how i wouldhave handled that.
You can trust your players to figure out what they can do pretty fast and if you dont want amnesia-5 to be the "my gm builds me a cool character"-flaw but rather like "damn, okay, i am a streetsam/mage/whatever, but how did i get here and why is nobody answering my calls? And who are the guys chasing me?" you have to let them work for every bit of info that is not about their abilities but about who they are and what went wrong.
The game can be a lot of fun then for all of you. (dont read on if you dont want the But, ...
)
Sadly,after the first couple of sessions it went downhill and we turned back to normal ahadowrun.
I think the main reason for this was that the players could not have a level of immersion they could have with characters they built themselfes. Maybe you could counter that with letting your players outline to you what character they want to play instead of just letting them name the 'class' they want to play as i did.
Another reason it didnt work out was the difference between the amnesia-game and our previous sessions. Amnesia (at least to me and my players when we talked about it before) is about finding out what happened and them seeking truth/revenge/refuge or something similar, where a normal shadowrun is about meeting mr johnson, legwork, planning and then the run.
My players did seem to tire from the lot of legwork they had to do in the beginning. I tried to build in some fight-scenes and datasteal runs to balance this as soon as i noticed and that at least stalled the inevitable.
In the end my thought was "well, that could have gone better and worse"
You should talk to your players about what you and they expect and plan accordingly.
Almost forgot: CanRay wrote a great story abound amnesia, the link is in his sig and i suggest it for inspiration. I dont know which one it is exactely, but i think it was called "a night to never remember". Just check them all out, they all are a great read.