You're right, from a pure user's point of view, there won't be many differences
Whether with SE or SMT, you will need a STEEM account anyway because SE uses Steem custom_json operations.
On Steem Engine, a user will need to buy STEEM then buy STEEMP(pegged/backed with STEEM) before being able to buy a SE token
With SMT, a user will be able to directly buy any token once he/she as STEEM.
Finally, saying that a token price depends on STEEM price is not both correct and incorrect. It depends on the intrinsic value of the token.
Let's say 1 TOKEN as a value of 1 STEEM and 1 STEEM is $1, so you basically can say that your TOKEN value is $1
Then the value of STEEM falls down to $0.5.
Without changing the intrinsic value of TOKEN, you now need 2 STEEM to buy 1 TOKEN (which still worth $1)
But if you consider TOKEN value kind of pegged to STEEM, then yes, its value is STEEM dependent.