I got on Betaseron when it..and Avonex (both interferons) were the only drugs available. And since I've done relatively well on it, my theory is, "if it ain't broke, don't fix it!"
Copaxone is relatively new ..and does show great promise. I think if you're doing well on it..and your doctor is confident about it...why change? It has the least side effects of the drugs available, too. I'd probably not switch unless I started experiencing a lot of exacerbations, or had some other compelling reason to do so.
My furkids..with a name like uppityCATS, you ask?? Four cats: Cindy, a momma cat who was badly abused before we got her, and all scarred up from being burned; Cassie, her "kitten" (who is now 5 years old); Tuffy and TabbyGrey, stray (and unrelated ) males who just showed up at our door one day (several years apart).
Spasticity is a very common usual problem with MS. More a "symptom" of the weak nerve impulses not getting through to your limbs (usually in the legs, but can occur elsewhere). What often happens is other muscle groups -- not "trained" to do so -- try to take over for the weaker muscles, and the poor weaker muscles (not actually weak, but just not getting the clear message from the brain!) try hard to do their job..and fail. And cramping (spasticity) occurs. It might well have been there from the beginning..just not as pronounced as it is now.
Anyway...as I always say..I'm not a doctor nor health professional; just a person who has had MS for a LONG time (25+ years); has had nearly all that it can bring, good and bad; and willing to share my experience with it.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....