I'd not use a lighter than reccomended arrow in any crossbow. Use of lighter arrows means higher shock & vibration in the limbs & this in turn can cause failure of the limbs due to the higher stress loads.

Given that Horton has now folded.

I'd suggest you extend the life of the bows limbs by use of a arrow weighing about 10% higher than the minimum Horton suggested. The 10% weight increase will give you:

Higher KE

Lower stress to the limbs

Lower vibration & noise when fired.

Usually a increase of arrow weight, over the minimum suggested weight, also gives a increase in accuracy.

There are several pluses to use of a slightly heavier arrow. ONE glaring minus in use of the lighter than suggested weight arrow. Speed is not everything.