Once you log into the steam version with your existing RoF account and buy a Steam DLC (and activate it) you are then locked to Sream and can no longer buy from the RoF webstore.

If you have a standalone game and use the webstore to slowly build up your hangar, logging in on Steam is not a good idea. It's a one way street.
And you will be locked into only buying DLC from Steam.

I have always advised people to stay away from the Steam Version

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