Worth bearing in mind that the 700s were still having teething issues (if I recall correctly) when the 707s were introduced, though both seem to be pretty much trouble-free now. Were the 707 problems software based?The 707s were just 700s with a different colour scheme and a few less vehicles, and they didn't exactly have an easy introduction! It's also interesting to see that these will be just single units, as opposed to 2 half-units, seeing as they've only got one pantograph
EDIT: Also, I hadn't really clocked that these will have a white front, essentially I just assumed all images were black and white, or the yellow hadn't been added. I have no problem with no yellow front, but these are the oddest I've seen, they look a little like a ghost, somehow.