I would say that Americans (and people in general) are more likely to attempt taking up those languages, if given a fairly equal choice between them and others that also require learning a new alphabet. For the same reason (although on a lesser scale) that they might shy away from Chinese or Japanese.
It's one more hurdle.
Chinese, if you don't care about writing it, is simple grammatically (though a few concepts are hard to wrap your head around).
So, for your proposed equivalence, I think my original statement is true, and I also think the more general statement above is likely true in a wider sense.
Initial attempt maybe. But I think very soon most people will find out that if you are coming from an Indo-European background, Kazakh or Finnish, regardless of script used, is far more foreign than Russian or German.
Thats how it feels to me at least when I think about learning another language. It's a data point of one, but I don't think I'm that unique in this.
And once you do start, something like differences between analytic and synthetic languages probably would be more of a tripping point.
Try Arabic, though. I took a relatively intensive four-week Arabic class one summer, and we spent the first week or two on the alphabet.
Anecdote: when I was little (in the USA), our family had a big dictionary, and in the back was, among others, the Cyrillic alphabet along with how to pronounce the letters. I would write out English words in Cyrillic letters, thinking that I was writing Russian words. :)
It may be a barrier, sure, but it is a microscopic barrier (33 letters, mostly Greek-based, many in common with the Latin alphabet) compared to the complexity of a language (any language) itself. Would you say that Americans would more readily pick up Danish? Or Finnish? Or Latvian? Or Polish?
Just as a side note: I once had to take a course in classical Greek. It took us one lesson (or maybe two) to learn the Greek alphabet. Compared to the rest of the course it was... I am finding it hard even to say 'peanuts', for it would be an offense to peanuts.
(I am more inclined to think that it's up to us to standardize on an international language — and I would much rather it were English — than for different nations to learn each other's languages. But that's, of course, just my opinion.)