Ubuntu – How to install proprietary ATI/AMD drivers on 14.10

I just upgraded to 14.10 from 14.04, and the built-in driver for my ATI Radeon HD 5450 sorta-kinda works okay because I do get a signal on my monitor, but it lacks any kind of acceleration, making the Dash and the menu reallly slow, and even typing this post has a significant keyboard-to-screen lag. What's more, the built-in drivers don't seem to support screen standby, so the monitor stays on forever :-/

I've tried several*) methods of getting proprietary drivers to work, but they all fail the same way: the boot simply ends at tty1 instead of going into the graphical mode.

Is the root cause that no 14.10-compatible driver exist? Or is there a "canonical" method that is proven to work, for ATI, on 14.10? _{(pun intended…)}

As far as I understand the matter by now, the problem seems to be that 14.10 uses X server version 1.16 but all the drivers only mention X server 1.15…

*) Methods I've tried:

• selecting the proprietary choices in the screenshot above,
• http://www.noobslab.com/2013/04/install-ati-amd-catalyst-drivers-in.html,
• Is my ATI graphics card supported in Ubuntu?,
• What is the correct way to install proprietary ATI Catalyst Video Drivers (fglrx) directly from AMD?,
• http://wiki.cchtml.com/index.php/Ubuntu_Trusty_Installation_Guide (yes, I know this is trusty and not utopic)