I have an 800 and bought one for my wife as well. I mainly use it for the normal bike computer functions (I replaced a 500) but I frequently upload routes to the garmin and then follow along. It does give you a pop up turn notification if you turn that feature on. For some stupid reason, you have to do that for each route that you upload, it's not a global setting. Also that feature sometimes mysteriously disappears and you just get a tiny little arrow and a beep as you go by the turn you just missed. Most of the time it works well. Another feature that works well in conjunction with that is "distance to next" so that you know how far you have to go before you start paying attention.

You can enter a destination and let it navigate you but that's not really what I use my bike for so I don't do things that way.

Recalculate works fine if you are going point to point, but if you start and end in the same spot, it will simply navigate you back to your start point as soon as possible - not really what most of us want, but useful in case you get lost.

The turn by turn piece is NOT as robust as the car Garmin navigation units, and I find that the map is very hard to read most of the time (it's a small screen, the colors do not contrast well and my near vision really needs reading glasses to read that thing, which I rarely cycle with)

I didn't/don't think the 810 is worth the extra cash even if you do have a smart phone to take advantage of the live tracking, but that's just my opinion. I found a bare 800 for 280 at (I think newegg) and I bought a 800 bundle from amazon for 380, and that included the HR strap, the speed/cadence sensor and the maps, which are usually an expensive extra from Garmin. I believe Garmin currently has a $100 rebate for the 810 if you'd prefer to go that route.