There are a few things that folks might want that they are not going to get in the DC 40.....
The two big things that didn't change are battery life with the fastest update rate and range. So far we haven't seen any increase in these and I am not sure we are going to in the near future.
Battery Life - I think the biggest concern with the Astro is battery life. We get around 17 hours of run time with the 5 second update rate. The concern here is that if you lose your dog at the end of a 10 hour day, you have 7 hours to find him before the battery goes dead. That's a little tight for me.
The thing to keep in mind here is that in my 4 plus years of working with the Astro, I have yet to be put in a situation where I could not locate my dog at the end of the day. It does such a good job, that I have always been able to find them. It still concerns me, but I am not sure it's as big of an issue as we think.
The DC 40 has added the option getting more battery life with a longer update rate (up to 2 minutes between updates) but I am not real sure I will go that route.
Range - More range is always better, but the MURS band that the Astro works on has it's limitations and right now Garmin is hitting it. If you were not happy with the DC 30's range, you will not be happy with the range of the DC 40. I am pretty pleased with how the 40 is doing but you need to be realistic about what your needs are when it comes to range and understand that the Astro may not be the right product for you.
In my opinion it works great for most folks in most situations. Folks that need extreme range (more than 3 to 4 miles) might need to look at running telemetry and the Astro at the same time.
If you are not sure, then feel free to try one out under our 30 day money back guarantee. The beautiful thing about the Astro is that it is easy to use and easy to test. You will know really fast if it is the right product for you.
I would like to point out that it is rare for us to recommend any other tracking system for the majority of our customers at this time.