actually the player who WASDA's most is getright :)
as i said, all maps apart from inferno are similar neither to 1.6 nor to source.
mirage is a purely 1.6 map.
dust2 was made from scratch, the only similarities it has to source is the direction of gates at long and B plant, lack of boxes at catwalk and lower boxes at T mid and B platform.
it also has significant differences from CS:S dust2: the box at short was lowered, which means it can't be used as a cover, which is the reason why CTs so rarely play at short unlike in source; the addition of new camping positions at both plants. the whole map was made from scratch, even the textures are different.
de_train is absolutely different to both source and 1.6: the A bombplant was moved; the trains are absolutely different, you can't go under trains; the B trains provide absolutely no cover which makes defending B plant a lot more difficult for both CTs and Ts; in source, it was easy to defend B plant as CT, but a pain in the ass to retake it. in source, there were barrels at alley which basically every CT used to defend alley. however in CS:GO they were removed, so now the way alley is played is very similar to 1.6. oh, and don't forget the new tower.
de_nuke is similar to source because it has fast vents and easier to use ceiling beams at A plant. however it has a lot of serious differences, a lot of which of which make it similar to 1.6.
for example, just like in 1.6, there's no yellow loader which was an imba position in source.
just like in 1.6, there are no sandbags at T platform above the T hut (no idea how it's called in english), which used to make the platform an imba position in source, always making it difficult to push ramp for CTs.
the gap at radioroom is much bigger in csgo than in 1.6 or source, which makes pushing ramp even easier.
the addition of white barrels at T house, which makes it a lot more difficult for Ts to defend squeeky from CT push.
the way outside and lower plant are played in CSGO is absolutely different to both 1.6 and source simply because they moved the backstairs.
they also added big barrels instead of boxes at A plant, which makes it different to both CS:S and 1.6.
all of these are keyfeatures which make a lot of difference to the map gameplay.
as you can see, all maps apart from inferno give no advantage to source players, and 1.6 teams can always veto de_inferno in bo1 if they feel they're bad at it.