Limited service life being how long the product is supported by the manufacturer.
Garmin doesn't support products much beyond their sales life. Furuno plans on supporting a product at least 10 years after they stop production. Garmin may offer repairs for a year or two at the very outside.
Failure rates on Garmins is pretty low. And with this small stuff, when it finally gives up the ghost, most owners will replace because the expense is so low.
As far as what manufacturers put on boats- it has very little to do with quality of the unit and is more about what the electronics manufacturer is willing to pay for.
Raymarine was on tons of boats at one point because they were willing to discount the product very heavily, and most boat manufacturers didn't have to pay for the product until the boat sold.
Garmin is now filling that market niche because Raymarine had money issues and couldn't keep going the way they were going. Brunswick, which was the largest buyer of Raymarine product that was factory installed went and bought their own electronics companies to try to get electronics at a lower price, and have a more "complete" integration of the product (similar to what they did with aquiring Mercury for motors).
They bought Northstar and Navman- two respected brands, and quickly ran them into the ground. They lost money, and dumped the product lines. Navico picked them up to go along with Lowrance, B&G and Simrad. Navman became Nortstar branded products, and both lines are now gone (although tye NSE designation on the new Simrad networked product stands for "North Star Edition").
Manufacturer's who are interested in having the best product on board tend to go Furuno and do so without any discounts from the manufacturer. Furuno product isn't sexy, but it works, and is built to heavier standards than the Lowrance and Garmin (or Raymarine) lines. I used to Joke that Raymarine wanted to be Furuno, Garmin wanted to be Raymarine and Lowrance wanted to be Garmin.
While Raymarine has faltered some (I think FLIR may be able to do something with the line), Garmin is indeed making inroads into the market niche that Raymarine had.
