These are all just options. The fact they have the skills and ability to handle/adjust/learn it, is great. They are both prospects that seem to have what it takes and show willingness to improve.
For example I played Center 98% of the time but if I was thrown out late in a game with a random line I would get put LW (right shot). I was the best Center for taking faceoffs most years so I would take all the important faceoffs and we would just switch (me back to LW) at the first opportunity. If I won the draw that switch would be instant. All these options help our team.
I shoot right. On the power-play I could play the left half-wall (stick in middle of ice), up high (either shot works), or in the low, one timer spot on the right side of the ice.
In the NCAA, that's what we saw, Caufield migrating to the left side to take shots from there. I recall him making those highlight goals from the boards over the G's shoulder (in a hole the size of the puck) on the left side.
Under MSL, he has been playing on the LW from the F/O dot onwards. It went from being an option to being a thing and Caufield has excelled at that position in the NHL so far. It also didn't become the glaring defensive weakness I thought it might become for Cole.
Roy has played RW for along time now and even became better defensively while playing his off wing. He's just so smart he can adapt and, if he can play at such a high level while still getting better looks for his shot on his off side, he should continue doing that.
Beck can be the winger that takes the F/Os and continues as the winger once we win or lose the puck, as you say, if we're looking house that talent in the dot, but I cans why some see a small (not 6'0" or more), speedy player with a good shot succeeding on the wing.
The key about size for a C, IMO, is his ability to win F/Os and battle for the puck one on one. Beck has a history of winning draws wherever he has played. Carbonneau was 5'11" as well and was one of the premiere F/O guys in the league for years. he was also quick (like Beck) and had smarts (like Beck) to anticpate developing plays and become a killer on the PK or at even strength by cutting passing lanes and stealing pucks together back on the offense.
Have some high hopes for Beck -- at C, but, obviously, if he has the skills to complete a top-6 line on the wing at a high level and provide a second F/O option at the same time, like with Dach as his C, it would be silly not to use him there.