I owned both of the units. I was never much pleased with the GPS on them. I up graded to a 899. I also have the high speed GPS puck on my bow unit (A HELIX 9). You didn't say if you are using the internal GPS antenna or not. I have both bow and console units on external. Other than that they are a very good unit, as far as the Helix 5 they are a good series of units. As I have had my 9 now for a year and want to up grade to a 10 on my console. I think you are battling slow update/refresh rates.