I gave my gen1 SPOT to my canoe partner when I bought the gen2. Both continue to work as they should. SPOT devices are required equipment by the rules during the Yukon River canoe races, and we had no problems with both of our devices in our voyageur canoe on any of our 4 race trips down the river so far. I don't see any real difference in operation and performance between gen1 and gen2 - but that is under open sky when on the river.
There are a couple of tips that may make for better performance. If you intend to go under tree canopy or areas with limited sky view, it will help to turn the unit on and make sure it is transmitting under a clear open sky view before you go under leaf cover. Give it at least 15 minutes of clear sky view if it has not been turned on in the area for a long time, or if it has been moved very far from where it was last operating. Once it starts tracking a strong signal, it will be less likely to lose signal when it becomes weaker.
Even more important is to understand what happens when you press the "OK" button. It can take up to 20 minutes for a signal to be sent out after you press the OK button. Often less, but still many minutes are common. Here's the important part.... if you press the OK button again before the previous signal has been sent out, it will cancel the first message and the 20 minute clock starts over again. Keep pressing the OK button that often and a signal will never go out.