I have a '10 GSA (late 09). Mid 2010 the urgh... Showa? I think suspension was replaced with WP components. Bear this in mind for comparison. Bought the bike with 4000km on the clock last January, now has 58,000km on the clock (didn't ride it for 6 months of that time as well). No problems with ESA, I've used all the main settings constantly, but don't often switch between soft/normal/hard. Terrain has been everything from 2up touring to 1up belting along to adventure riding complete with water crossings etc.
I wouldn't go back to standard suspension. How many hop off their bikes as we go from seal to gravel and give a few turns here, couple of clicks there? I sit on the bike, push button, suspension changes - and it really makes a difference.
On the downside, the suspension is not serviceable, so at some point it has to be replaced. Another set from BMW is bloody expensive, and you'll still replace in the future again (I do a few km, so this is a factor for me). There is no service interval so how long it will last is based on usage and guessing. I hoped I would get 70,000km+. After reading some comments by others, it was clear the performance of the suspension was detoriating faster than I thought, most noticeable was the increased dragging or touch down of stands on bumpy roads.
This weekend Ohlins EC is being fitted (first in NZ). On an introductory price it's actually cheaper than a BMW set and serviceable. As far as I can see, it's the most expensive whizz bang option amongst the aftermarket (including speed-based dynamic adjustment if you're on comfort mode) but the others don't have any agents near me, Ohlins has one of the best. You do lose the front preload adjustment (no aftermarket has this), but I've had normal Ohlins before and the performance is head and shoulders above the rest... Full adjustment of Ohlins isn't available yet, Ohlins is releasing the tools to agents later this year. I have gone for a spring one step heavier on the rear.
Have to see how it goes of course...
Warning: My post quality varies according to my mood. If I sound sane give it a few minutes and I'll be back to normal