The Acewell has a digital readout and I've found that it needs to sit at a certain angle to be perfectly readable, especially at about sundown. My only beef so far is that the small indicator lights are a little hard to see under direct sunlight.
Laying the Acewell flat in a /5 housing would likely render it unreadable.(?) But I never tried it...
I really like the gauge so far. The speedo is dead accurate when calibrated and the two trip odometers are a good addition.
Since this photo I tipped the housing back a tiny bit to find its' "sweet spot" for better visibility.