We've just switched off the mobile optimized interface for all retail web sites. Maybe its just me, but I find the desktop one easier to use. Love to get your opinions on it as you guys use it a lot more than I do!
I've always switched to the desktop version when browsing on the phone.
The only problem I've had is that mobile version doesn't show the stock status without clicking on the actual product, the desktop version shows it at a glance!
On my mobile I always prefer the desk top over the mobile interface for all web sites. :)
Prefer desktop version on mobile, once you know an item is on the site, it becomes immaterial which platform you're using.