Early DC14s in the lighter silver - same as DC07 were less durable, more prone to breaking etc.
The later dark steel DC14s are said to be much stronger and more durable. Ive noticed personally between my old early model and now later model the plastic feels much stronger and feels like it can take more abuse than the older.
I have a yellow dc14 (labeled DC14 for carpeted homes) which had the lighter silver, early wand, chassis etc. I later bought another yellow DC14 (DC14 origin - it was a re-labled version of what I already had but with much less yellow)
because of the stronger feel I swapped over my plastics for the newer ones and sold the other. Side by side you can tell the difference and when used to the newer dc14s, handling the older dc14s feel like its much easier to break and snap.
So in conclusion: The lighter silver DC14 are said and do feel less durable and more prone to breakage in comparison to the newer 'dark steel' dc14. I much like the DC14 and personally feel its quite possibly the most durable dyson made to date.