TL;DR: buy a Foretrex 601 if you can afford it, otherwise get a 401 or 301. Buy used off ebay or tacswap
In almost every photo of me in the field you'll see a GPS on my wrist. Not gonna go in depth here about why it is an essential piece of kit, I hope you already know that. I'm here to help you navigate through the various models and buy one that does the job for you.
WHY NOT A NEWER GARMIN/SUUNTO GPS WATCH?
Yes, I know about them. Yes, I've looked at them (a bit). The reason I don't use one is this: hotswappable batteries. Every single GPS watch I've seen has an internal battery that can't be switched. After it runs out of juice, you need to plug it into a power source with a little USB cable and wait for it to recharge. Until it recharges, you can't really wear it on your wrist to navigate with. A Foretrex on the other hand is powered by 2x AAA batteries. When it dies, take a knee, swap out the dead batteries for a fresh set, and in 60 seconds you're rebooting your GPS and getting back to navigation. I also have some gut distrust about the moisture and impact ratings on the newer GPS watches, but that's probably just paranoia.
So let me take you through the lineage of the Garmin Foretrex:
GARMIN FORETREX 101
-15 hour battery life (2x AAA)
The original Foretrex, launched around 2003 as far as I can tell. Has most of the functionality you need for land nav, but GPS responsiveness is noticeably worse than later models. My 101 loses signal somewhat regularly. They also have a shorter battery life. Buy these if you find them for cheap to hand out in an emergency, but I'd really only use one if I had no other choice.
GARMIN FORETREX 201
-15 hour battery life (internal Li-ion)
Garmin's attempt at putting an internal lithium ion battery into a Foretrex. Launched around 2008? This obviously makes the battery not hot swappable, so not suitable for serious land nav IMO. I'm not the only one that thought this, because later Foretrex models go back to AAA batteries. I briefly owned one so I CAN talk shit about it.
GARMIN FORETREX 301
-18 hour battery life (2x AAA)
AAA batteries, and much better GPS connectivity and responsiveness than the 101. These launched in 2009. The 301 is a good unit. I have a couple of them in my kits and they are quite reliable. Also has a smaller footprint than the 101.
GARMIN FORETREX 401
-17 hour battery life (2x AAA)
Launched around the same time as the 301 as a sort of "deluxe" model. Same footprint, but it has an electronic compass and barometer (earlier models relied on some other method to calculate these that are perhaps less accurate?) It also integrated with some of Garmin's other products at the time. The downside is an increased cost, and a slightly shorter battery life, though in practice I haven't really noticed it with mine.
Doesn't exist AFAIK. Not a peep about it online. Guess they just skipped this number. But imagine what could have been...
-48+ hour battery life (2x AAA)
"Garmin Foretrex TL;DR If I have a 401 should I get a 601? No. If I don't have a foretrex or a model older than a 401 should I get a 601? Yes.
The Foretrex series of navigational devices have been a world standard in navigation the world over. You will see persec'd images for over a decade of some of the best military units in the world using these devices. Let alone search and rescue folks and through hikers. However I digress, Nixieworks has been a proponent of the 401 for quite awhile, they reached out to me with my use of the 601 as a comparison. On the surface they appear to be very similar... they are, however, separated by several major features.
The 601 has the following major differences:
1. 48 hours of battery life in GPS mode on the 601 vs the 401 17 hours
2. Supports all major satellite networks (GPS, galileo, glonass)
3. 3 axis compass and accelerometer (orientation of the device doesn't matter)
5. Nicer screen with maps(using software on your PC to preload maps and waypoints)
6. Last and most least bluetooth (ew) but it allows you to easily update the unit OTA
For me that is enough for me to make up my mind towards the 601, however you can get a 401 for a song and a dance, and buy several used as backups for your family and friends.
I have used the 601 on several hikes thus far. Getting used to the interface is a slight challenge; it certainly does not work like your cell phone or smart watch. Not updating my 601 was a mistake I made. I was having insane satellite connection issues on an entire trip. This was resolved in part by a firmware update, and that GLONASS doesn't exactly work right now(this may have something to do with the war). Setting this system up to strictly use the combination of GPS and galileo has been the ticket for my use. I won't put my final stamp of approval on a device until after a year of use. However plenty of people have already done that in the industry, so don't hold out on my word.
Thank you for reading.
-48+ hour battery life (2x AAA)
Similar weight, battery life, and footprint to a 601. I'm sure it's great, but it's also $500. Doesn't come up used for good prices ever either. It supposedly has a whole ballistics computer in it, but I'm not a precision rifle nerd so I don't care. God and Eugene gave us thirty round mags for a reason 💪🏻
If money is good, get a 601. The extra battery life, better GPS responsiveness, and added software features make it worth that extra $50-100. If you're on a budget, get a 401 or a 301 (401 preferred). If you are in a pawn shop and see a 101 for $20, buy it to hand out to your conscripts in an emergency. Note that ebay and tacswap are both good sources for finding these at a discount. Don't be afraid to buy used ones, they're usually fine.