I have the older digitroll 4's so I had to go to the web site and down load the manuals for both units. If you want bottom track you need the new 10's. The fives will connect to the bottom line depth finder. This allows the captain to control up to 6 downriggers from one stop. This is a set up that is used mostly on the great lakes where you can fish as many rods as you want. It is not uncommon to see a boat with 10 or more rods running at once. I read a articale by a great lakes charter captain that runs up to 16 rods at once including long lines, side planers, jet divers and down riggers all at the same time. :shock:
Around the PNW we are only allowed one rod for each fisherman ( there are exceptions) so the most down riggers I see are four but most people I know run just two. If you are running 2 in a small boat then there is no need for controlling them from a fish finder.
The new digitroll 10 is the one you want. There are always older digitroll 4 on ebay and some times on craigslist. Cannon has a great lifetime warranty on external parts. I have two new reels installed on my used craigslist downriggers for free.
If you want to try them lets get together and fish my boat some time in Feb.