Should I buy an htc One or wait?

I finally decided to replace my 2 year old Nexus S. 512 MBs of RAM just arent't enough anymore and IO speeds seem to have gotten pretty bad, making it SLOW. Custom ROMs and kernels have helped a bit, but not that much. I'm in the market for a high end big screen device, off-contract. The htc One seems like the most tempting proposition to me, with decent specs and high build quality.

Thing is, it's already been about 6 months since this device came out, so should I buy it for 500 euros (off contract) or should I wait for new devices to come? I don't care for phablets like the upcoming note 3 or the one max, I want something between 4.3 and 5". So far, the only device I see coming is the xperia Z1, but Sony's track record isn't exactly clean (the xperia z had quite a garbage display) and god knows when they decide to release it (it hasn't even been announced, that's september 4th at IFA). I tend to keep my devices for quite a long time, so I would really appreciate it if it will still be acceptably fast in 2 years time.

Should I make the move? I'm thinking that since the verizon htc one has just been made available and there is no word yet for its successor (or a new nexus device), it will probably hold up pretty well for quite some time.