HDXB101 success
I promised to post the outcome, so here it is.
With Netgear my network hardware manufacturer of choice, my guess was that the HDXB101 was what I should have purchased in the first place and I couldn't have been more correct.
No brittle cheapie-cheap plastic, no fiddly buttons (in fact none at all), no quaintly written instructions, and no defective devices on unpacking.
Plug, pause 30 seconds, and play, and if you are not worried unduly about security then that's all you need to do. I have however installed the configuration utility (which also automatically checks back to Netgear.com that the adapters have the latest firmware) and configured a different network name. This simple change automatically changes the encryption key which is a nice touch. The only other setup change that I made was to name each adaptor after the device that it connects to (so HomeHub and DG834G) simply so I know which is which when checking performance using the utility in future.
Because one of the MaxValue devices was broken I never got the opportunity to assess performance but the Netgear devices are great.
Advertised as up to 200 Mbps, the configuration utility shows that I am getting between 140 and 190 Mbps Tx and 118 and 170 Mbps Rx when on the same mains ring, the lower end of which still supports HD video data volumes and bodes well for when I link the media center PC in my office to the AV equipment in the lounge (same ring).
Although I do not envisage needing to do it (because per my original post I will now be able to optimally position the DG834G to wirelessly cover the entire house and garden) when running across rings (I have three for power sockets) I am getting between 100 and 128 Mbps Tx and 45 and 95 Mbps Rx; although the bottom end of these numbers is too low for HD video streaming it is still more than enough for normal data traffic should I ever need it; web browsing has no detectable performance difference whether wirelessly to Home Hub or DG834G (and then back to Home Hub via ethernet over mains) or ethernet to either device.
Add DAB's usually competitive pricing (even if not the cheapest, cheaper than Amazon this time) and same day dispatch and I am a very happy punter.
HDXB101s come highly recommended.