Pros and cons.
I don't have much to say about the surge
tank. I think it's one of the better ideas I've seen in a long time, but... the price tag is a bit of a shock. A C-Note seems pretty steep for an add-on device.
The GLV-3. That's a nice device and has a solid following. They hold their resale value as good or maybe better than most high-end mods. Again, the price tag is on the high side for a device with plastic components. And, availability is often an issue. Every time I've tried to buy one, I was unable to.
The V-mod. I bought one and used it for a few days. It looks nice - vapes well - and the feed system isn't too difficult to get used to. I like the price tag a lot. The major con for me was that it's plastic. It is slid in to an aluminum shell (and you can get the shells separately so you can have a color for every mood) and it feels pretty good once it's all put together. But, my lifestyle is really tough on plastic devices. It wasn't for me.
The REO. Great device. I have a REO Mini and a REO VV Woodville. The REO VV Grands will be for sale in probably 4 weeks. If you are seriously considering a REO, and since you've already used an advanced device, I think you should wait for the VV Grand. My VV REO Woodville is one of my two most favorite PVs. I can't give you any cons on that one. They don't exist... I guess, though, since I mentioned it for the other PVs, I should say that $205 was a little hard to part with for a single device. I don't know what the price will be on the VV Grands. I do sort of expect them to be a little less than the VV Woodvilles, but any guess would be pure speculation.
Two other feeders to throw in the mix just to make things more difficult:
If you think wood is an acceptable build material for your next mod, The Boggers Box Mod is a superb wood bottom feeder and a really good value. They do have a VV model, but it can get just about as expensive as the VV Woodville (depending on what wood/options you choose) and the VV isn't nearly as easy to use as the Woodville. It requires a little screwdriver (provided with the mod), and I've been told the opening for the screwdriver is tiny and a little hard to use.
The other is not a bottom feeder, but rather, it's a top feeder. The VVPV from notcigs is my other favorite device. I can't say enough nice things about it. There are two cons I can list, but neither one has anything to do with the device itself. The first is the drip tip adapter. You have to buy it separately. The other con is that it looks like it is still taking notcigs as long as three weeks to build and ship some of them. It's worth the wait, but it's good to know that ahead of time.