for/do doesn't work in OFP so you would need to use while/do, and I believe in OFP that is limited to 10 000 (or was it 1000) loops and with a pauseless loop that limit is reached very fast as the loop loops on every frame.
When the loop limit is reached you will get a error message, IIRC it was 'generic error in expression' or something like that.
And as the sqf functions in OFP pause the game/other scripts/whatever during it's execution having it perform a longer pause might give you pretty odd results.
Besides, the sqf function in OFP is completely different thing than the sqf script in ArmA, they differ in execution and interpretation (other pre-compiled, the other read 'on the run').
The latter was designed for ArmA to replace the horrid sqs scripting and works basically the same as sqs only performs more effectively, whereas as already pointed out, in OFP sqf serves a purpose of a function which generally is used for a fast and short data manipulation to return a value. Of course the returned value is not mandatory, but the key word is short and fast.
So I'm sorry, with OFP you're stuck with sqs. Of course you can still use functions as much as possible (called from an sqs script) but the performance benefit due to the completely different design than a sqf script might turn to negative with too extensive use..