There are 2 differnt types of back deck rolls in those videos, one that ends forward and one that ends back.  The ending body position actually makes a big difference in the hip snap, which is were you have your problem.

In the first video where the guy ends up on the front deck, the backdeck roll uses only a sweeping roll.  in the second video, the roll is a modified sweep/c-c roll.  You can see that he starts by sweeping around the back deck, and then there is a defined moment where he snaps his hips and finishes like a c-c.

Your hip snap problem- In the sweep roll that you need to use to get to your front deck, your hip snap is more gradual, spread over the entirety of the sweeping movement of your paddle.

1) the finish I'm doing seems more risky for the shoulder than the forward finish
What do you mean more risky?  W/o having seen your specific roll... there are a lot of little things that can put your shoulder at risk.

2) I'd like to finish forward just because it's another way to get up and I'd like as many different ways to get up as possible.

I honestly use the backdeck roll about 90% of the time, ending forward.  There are 3 major advantages I see to ending in a forward position...
-Your body and paddle position have you ready to take another stroke
-If you do not make your roll, you can easily tuck forward and protect your face and shoulders
-I feel that once you get it down, the sweeping backdeck roll is the most powerful roll out there.

If you are interested, here are a couple clips of my backdeck roll in WW on my vid at 3:00 and 3:22.  I might make some vids in the pool next session and post em up.
http://www.youtube.com/watch?v=bB2qVcSRDSI

Backdecks DO leave your shoulders and face more vulnerable
shallow water + backdeck, not such a great idea, know that you wont punch the riverbed with your grill.

http://www.youtube.com/watch?v=4DzX3xL3izo