Replacing a GPS : New maps or new GPS?

I have a Garmin Nuvi 200W which I like, but I'm finding more and more mistakes in the maps. Turns out map updates are $69. A newer model, the Nuvi 255W is available for $99. It has a faster processor and locks onto satellites faster. The old Nuvi 200w becomes the backup GPS/photo frame and the 255W takes its' place.