OK. I've been reporting this for a few weeks, but now I will confirm that it is a hardware issue.

A buddy of mine got the new HS puck and reported these same discrepancies between his unit connected to the HS puck versus his ipilot remote and his lowrance unit at the bow.
I've see discrepancies between the puck versus my ipilot remote and my 898 console unit. The ipilot and console unit will be exactly the same speed but the HB 898 connected to the HS puck will be off on occasion.

The console unit is updated to the latest revision similar to the bow unit.

We were both slow trolling at around 0.5 mph with the HB unit connected to the HS puck showing speeds around 0.2-0.3. This is only occasionally, but noticeable.

I'll be making a call on Monday.