I didn't mean to scare you. It just seems that, no matter what the symptom is, the response will be 'my tranny did that a week before it died.' I swear I could post, 'tranny shifting normally,' and I'd get ten 'save your pennies' replies.
To be fair, my wife's Legacy (very similar tranny) has a hard 1-2 upshift when it's cold. Other than that it's perfectly normal and strong.
Flushes, if done properly and early, can be effective. I think the majority of failures that happen immediately after a flush (mine included) can be blamed on other factors - like the tranny going too long without being serviced in the first place. With only 35k miles on yours, I'd consider it safe. Flushes which simply have the transmission draw in new fluid while pumping out the old place no extraordinary strain on anything - it's just how the tranny operates every day, except that it's getting new fluid back instead of old, slightly cooler fluid.
Yes, SVX trannies can and do last awhile. Mine failed permanently at about 133k. That's hardly stellar, but it is above average for an SVX.