Is the only difference the digital screen size?

Another difference is the sg3 uses AA batteries vs a rechargeable li-ion. I chose the SG3 because of the AA since you can buy batteries anywhere

I have heard that the sg3 is not the one to get even though it cost less since you have to buy new batteries after about every 36 holes. With Sg4 you can simply recharge.

Since I have a digicam, I also have rechargeable AA's, so my cost for a battery is negated. I have about 20 rechargeables AA that I use, remotes, sports gear, digicam, and skycaddie

I have a SG 3 also and i bought rechargeable batteries for it and have no issues with it , i thought the battery pack was the only difference between the 3 and 4 but dont quote me on it ...

The screen on the sg4 has four different grays instead of just two and it has a rechargable battery. I think using batteries is much simpler and much more failsafe, so I went with the sg3.

I have the SG4, and it's a pain in the A!@ to charge the battery (or to remember to), especially for that last minute decision to go hit the course, you get there and your battery is dead. Would prefer replaceable/rechargeable AA's. The SG4 does have an sd memory card slot, the 3 may have one as well not sure, but I have not figured out any valuable use for the memory card, as sky caddie has us all bent over with their membership plans and # of courses that can be stored in the internal memory. If anyone knows how to take advantage of the extra memory, please advise.

Maybe a silly question but... I also have an SG4 but where is the SD card slot???? And how old is your model, early 2007 or mid 2007?

sd card slot is UNDER the bettery pack, inside the SG4, like the way a sim card goes inside most cell phones.

it's not hard to remember to charge it. just plug it in when you get home!

Wasn't the case for me. I use my SG3 with fresh batteries for about 5.5 rounds before I have to change them.

Does the Sg3 have iGreen?

Love the rechargable SG4. Lasts forever too.

Yes, it has iGreen. I get about 3 rounds on my rechargeable AA's in my SG3.

Love my SG 4. You just have to remember to charge it after a few rounds...

I just snagged a brand new SG3 of ebay a few minutes ago. I went with the SG3 because of the fact it uses AA batteries. From everything I have read, people are getting great battery life from the AA. I also plan on keeping a couple spares in my golf bag just in case. I'm pretty excited to get it and start using it.

You won't be disappointed

Does anyone have successfully store downloaded courses on the SkyCaddie SG4 SD Card Memory Slot?

I've used my SG3 for approx. 250 rounds. I usually get about 2 and half rounds with regular batteries. I've tried the Energizer Lithium batteries too. They are more expensive but the will last about 4-5 rounds. The battery meter will show fully charged the whole time but when the lithium batteries start to die, they die quick. Usually in a couple of holes after the battery meter starts to go down. Regular batteries show the meter more like a cell phone does as the meter will go down slowly.