It really depends on what type of fishing your doing. If you like to troll all day then the digital maximizer can almost double your time on the water. I give you an example, I have a 55lbs endura transom mount, two walmart group 29 batteries and I can troll about 7 hours. This setup requires constant steering and gives me a backache. Now if I use my 55lbs Ipilot pd which has the digital maximizer and the same two Walmart batteries, I can troll up to 12 hours. And the Ipilot is way less work. Record a 2 mile track, set the cruse control at 1.5 mph and just sit back and let it do the driving while I concentrate on fishing.
Happy shopping
You didn't mention what type and size of boat your have? And, are you sure a 45lbs motor is going to be enough?