I didn't say I couldn't read the Speedo but it seems some have trouble reading the question!
Does anyone seriously believe a small analogue display is more easily read and interpreted accurately than a large 1, 2 or 3 digit display, or are they "arguing" for arguments sake?
I've been riding for over 50 years and can judge my speed reasonably accurately (only done for speeding once - in 1984, in a car) but as some have pointed out, knowing your approximate speed isn't good enough today, particularly within 20, 30 & 40 areas and average camera zones.
For those youngsters who don't yet need reading glasses, your time will almost certainly come quicker than you think.
The large digital readout on the Nav 6 or TFT is simple to see, and interprate, easily and is much less distracting than trying to get an accurate reading from the small analogue display.
Thanks to all those with practical suggestions, perhaps a small tablet (I have an old 7" one) with a speedometer app would work.