I've had a 405 for a couple years and recently got a 110 as a replacement. If you're anything like me then after the initial excitement of all the features of the 405 (advanced training programs, etc) you'll probably find that you don't really need them. I found that I don't even really need to know instantaneous pace. I mostly mostly use the watch as a recording device to record the running that I do by feel. Occasionally it's nice to know pace for intervals of 6 minutes or less, but average pace is fine for that.
After about a year of every day use, the battery on the 405 will not hold a charge for very long. My 405 also spontaneously resets every now and then. At this point it's still functional but not reliable any more. I would not count on it to work if I really needed it. This may be the case for all garmin watches, which are basically disposable. I think Garmin counts on people replacing their watch every year, so they don't design them to last much longer than that.
The 110 is great because it's cheap and it has basic functionality. If you consider that basically they're disposable watches that will have problems in a year, you might as well get the cheapest one. It's going to get banged up, rained on, sweated all over and the built-in non-serviceable battery has a limited lifespan.