You could always get one of these, one of the best reps made in my opinion.
Caseback is a damned site (sight?) more accurate than the Senna too (although for some bizarre reason mine has the model number of a non-chrono on it - everyone elses seems fine).
As Andy pointed out the Tachymeter function can also be used to track KPH if you use a Kilometre as the unit of measurement. Some watches (like the Chromomat Evolution) have both on the scale so you can convert between the two, so at the 12 o'clock position it has 100 and 60 (although by my reckoning that is not quite accurate).
I have small wrists and don't have a problem with my UPO or SFSO. As someone above said it's personal preference and what you feel comfortable with. Here's wrist shot of my UPO, my wrists are somewhere around 6.5.
This was the main thing that stopped me buying a rep moonwatch and pushed me towards a gen. For gens I've read of people swapping out the Hesalite for Sapphire on the standard 3750 but it isn't cheap, not heard of anyone do it to a rep but I am ready to be corrected. 50th Anniversary is meant to have domed Sapphire (but not a display back as on that rep).