It's hard to say. My experience was that it fluctuated between 3 & 4G. Your experiences may of course be different. I'd go to a dealer or a current customer in the area and see what they're getting. Some of the posters here bought boosted antennas. -something to consider.
Sandlapper, thank you for your inquiry and I agree the map can be a little confusing. If your area shows extended 4G, this means you will mostly pickup 3G in this area. It is possible you may sometimes get 4G based on distance from towers, but mostly 3G.
Sandlapper, your best bet is to just assume you will be 3G. You may get lucky and get 4G signal but it will flucuate widely and the devices will consistatnly switch between 4G and 3G (something verizon devices don't do well.)
I am in such an area, when I get 4G it's 2-3 bars (but not very strong by the numbers, can't remember the exact strength numbers but it's low) it will then just drop off and then come back. The device won't switch so I end up locking it to 3G or locking it to 4G and hoping it doesn't drop too much. I have tried the external antenna but in my case it didn't help I got much higher burst speeds but still had the problem with reliability of signal.
Obviously your mileage may vary, but this is my experience.
I have the samsung hotspot. I am in 4g extended coverage area and my device switches between 3g to 4g every 1-2 minutes, and never holds the 4g connection longer than 45 seconds. My 4g signal strength fluctuates between 100-112. When I have a solid 3g signal I am in the area of 90-100. I have talked to verizon multiple times, this is my second samsung device, the first one they deemed as defective over the phone and sent me a replacement. The replacement hotspot immediately did the same thing that the first one did to a tee. I then spoke to verizon tier 2 tech support for almost 2 hours and they opened a "problem ticket", which I knew would result in nothing since I have experienced "problem tickets" through verizon in the past with no results. So, now I'm stuck with a device for two years that wont hold a 3g connection for more than 2 minutes (kills internet connection when it switches to 4g, and vice versa when switching back to 4g.) The real killer in my situation is that I just bought a iphone 4s through AT&T and get a steady 3g signal and can hit 3mb/sec download, and 2mb/sec upload, ping 110-150ms. Destroys verizons speeds in my area. With my verizon Samsung hotspot I have never seen download speeds faster than 1mb/sec, .50mb/sec upload, 200-400ms ping. I wish verizon would do something about my problem, but I feel as though they are just going to sweep this issue under their massive rug.
"Problem tickets" = No help