If I played The Witcher on steam, and then was to play the GOG copy of Witcher 2 would I have any trouble importing my save from the first?

No, but little carries over. Maybe some dialogue, but I got the sword i beat Witcher 1 with.

You may have to move files around into different directories if they don't default to the same save location, but I believe you should be fine otherwise.

So I imported my save and it didn't seem super significant. I came into the game with some items that I wouldn't have otherwise had, but that seemed like about it. Anyone know if anything more significant carries over? I'd try to look it up myself, but I'm not in the position to at the moment.

Should be fine. Only minor stuff carries over, but there is one larger element towards the end that changes based on your choices in the first game.

Some choices will be different if you don't carry the save over. For example, at the beginning of the game, King Foltest mentions that Adda is dead, even though you can save her in the first game. (Just a choice in the first game). So yeah, I'd definitely get those saves to transfer if you want everything to feel more cohesive.

If you can find your save files from The Witcher 1 then it'll be fine. They should be in Users\<yourname>\Documents\The Witcher\Saves. Apparently quick save never copies over itself in that game, because I have 687 saves. 12Gb of Witcher 1 saves :/

Don't expect a Mass Effect style carry over or anything like that though - Witcher 2 is practically a fresh start.