GPS Combo Live charting / bathymetric charts

 Hi all,


thsi may have been asked before, but i couldnt find any info in the search.

Im about to pull the trigger on the Garmin sounder/GPS.

I am keen to try out the QuickDraw contours on the Garmin, but wondering if anyone has used this (or comparible function for live drawing live charts).

How long will it save data for (can you have a few years of maps saved on it)?

Does it slow the unit down at ll once lots of data has been saved?