The speed pulse is needed for dead reckoning

Dead reckoning is used...

for the first seconds to minutes after switch on before a GPS signal is acquired (you can easily drive 1km in this time)
under bridges
in tunnels
in underground carparks
in built up cities with many skyscrapers and poor satellite reception
in very bad weather with weak GPS signal
and many other situations where GPS signal is interrupted.

Use at the VERY LEAST the speed pulse!

The reverse signal is only for when you go backwards.... but that is so easy to connect, there is no excuse for not using it.

No Dead Reckoning = Disappointing GPS performance

With Dead Reckoning = Perfect GPS Performance

You choose.