I own a 2 2610's, a 2710 and a Nuvi 855. Out of all of them the 2610 was my favorite, however the operating system is not of the current breed. The 2710 has the same operating system as the Nuvi and Zumo of the current day. One of my 2610 is a brand new factory refurb, waiting for everything else to break. The 2710 I got accustomed to and found most of the functionality of the 2610 someplace in the menu structure. The 2710 is also a factory refurb with very little use as well. I take this and the Nuvi on my tours. Never thought I would ever see the reason for 2 GPS's but I did and love it.
With all of that said, I now take the Nuvi 855 with me on most of my short trips. It essentially does everything the 2610 and 2710 does and was only 85.00. Not waterproof, but the rain has not bothered it at all and those times it is really raining, a plastic baggie works well. I do miss the voice commands from the Streetpilots. I use the garmin adaptor with the speaker to charge up the 2610/2710. The speaker was set such when I heard a voice I knew to look down at the GPS for an impending change of direction. Don't really need to understand the voice command, just need enough noise to let me know I should look. I occasionally miss a turn with the Nuvi, but it recalculates so fast that it makes up for my mistakes.
I use my GPS pretty extensively for taking me to places for the various grand tours that we partipate in and the other crap I chase like National Historic Places and Landmarks, Other odd ball places ya gotta visit before you done, etc etc. So I rely heavily on the GPS's routing capabilites and MapSource. All of the GPS do a very good job in this regard. Finding gas stations, motels, food places work in all. The 2610 was the only one that could tell me how far the next exit is on an interstate.
The Nuvi (and I will make a leap here) and the Zumo's routes from MapSource are loaded to the units differently than the Streetpilots. The Streetpilots would load the route intact from MapSource. (it seemed it was loading the GDB file versus the GPS file) The Nuvi loads the points of the route and when you import the route it calculates its own route based on the preferences within the Nuvi. I believe the GDB file is converted to a GPX file when you send from MapSource to the Unit. No big deal, just different. This requires you to be more careful in planning routes in MapSource if there are roads you just have to ride on. Make sure you place a routing point on these roads.
I can't bring myself to pay 500+ for a Zumo, when any Nuvi that accepts routes (not all of them do) will do the job. Like I said I bought the Nuvi from woot.com for 85 and have been happy with its dumb down abilities comparted to the StreetPilots.
You use to be able to get your 26XX 27XX and 28XX fixed by Garmin for $100, however I think for the most part they have stopped performing this service.
My 2610 screen shriveled up after about 3 years, my 2710 screen shriveled up after 2 years. Both times I left the unit on the bike outside in September on one of those nights where the temps dropped from 70's to the 30-40's and was misty out. On one of my 2610 shrivel ups I ended up fixing it myself with some transparent vinyl from JoAnn Fabric store. If I was to do this again, I think I would get the translucent vinyl to cut down on some of the sun glare.
When I do my multiday tours, I have the best of both worlds, since I mount up the 2710 and the Nuvi. My guess you will have to look for a used 2710 on craigslist or ebay. Make sure you can register it with Garmin so you can unlock the maps or have the Unlock codes with the unit. Given you might not be able to find a Streetpilot, I would look for a cheaper Nuvi for under 150.00. Walmart carries them now. Hope this helps.
With multiple GPS's you WILL end up with multiple maps in MapSource, which you gotta remember which one goes with which units. The Nuvi is far more forgiving in this regard than the Streetpilots. (again the difference between how the units are loaded with routes)
Willie