Depends on how you will use it
By a "repeater" are you referring to just an alphanumeric display of Lat/Long, or something more graphic?(1) An alphanumeric display of Lat/Long only gives you something to plot on a chart, so if you regularly navigate/plot from the cockpit it would be convenient. On the other hand, think of how often you usually take a position & plot it? If once an hour or so, and you have someone on the helm, then it probably isn't worth the expense.(2) A graphic display that shows the "roadway" on a route is convenient to steer to, and that would be worth the bother in my estimation.(3) A full chartplotter with digital maps is better yet & definately should be near the helm, not down below.On my boat, I have a Raymarine integrated instrument package. It includes chartplotter at the helm & an alphanumeric all-instrument repeater below at the Nav station. The chartplotter is integrated with radar & GPS and digital mapping. It is very convenient and it's use on coastal passages, etc. (day & night) has been worth the expense (to me). At the Nav station, I take the readout & plot position on passages. The repeater also gives wind, depth, bearing, etc.--Ron