I have to agree with Bill on all his points, the difference in machines is more apple to oranges, and it really comes down to how much you want to spend and what you want to do with it. I started out I was looking at 12x28-36 or smaller, and I ended up with a 1340GT and spending almost twice as much as my original budget. I also had "0" experience with VFDs. So maybe a few comments and suggestions, we all see things differently so it is all shades of grey.
1. In general, a Taiwanese machine is going to cost something like 25% more, the difference is in the details and the fit/feel of the machine. Compared to the less expensive Chinese machine, they will both give you a finished product and hold similar tolerances at the end of the day. But there may be a number of annoying idiosyncrasies or palpable difference in how the controls work and the user experience. Myself, I had a higher quality Chinese mill that I used for years, but I put a lot of work into making it better. I sold it for a Taiwanese knee mill, and I will never buy a Chinese machine again. That being said, I had more wiggle room on the budget and I saved through the years for the upgrade.
2. I think there is a lot of merit in going with a 3 phase machine for a number of different reasons. It is generally accepted that the surface finish on a 3 phase machine will be better and you do not have an issue with the failures seen with single phase motors, usually due to the capacitors failing or the starter switch. When you are doing operations that require frequent on/off motor cycling, the start capacitors tend to go quickly. Single phase Chinese motors are notoriously bad for failing in a year or two. On this one, on a lathe, I would only go 3 phase. You also have the added issue on the 1340GT that it is not easy to drop in a 3 phase motor at a later point, there are very few motors that will fit and they can be pricey.
3. VFDs are an adjunct and make life easier in dialing a sweet spot and have a few other control features that can make you life a lot easier. If you are old school and run an RPC, that also works just fine. Cost wise you can put together an RPC for not very much, so a few hundred dollars and you are up and running. You have probably been getting some misinformation on the speed range of VFDs and what works, along with the belt changes. So the stock 1340GT 3 phase motor is very decent, a reasonable operating VFD range is 20-90Hz in sensorless vector mode. Keeping the 1340GT belt on the low speed belt range, you are probably talking a speed range of 40-1200 HZ. I never had to change the belt position on mine, and even if I did, it would have taken about 2 minutes to switch speeds. Using an inverter motor, I use a 20-120 Hz range, with a single pulley, I have a usable spindle RPM of 40-1800. I have never been able to bog down either motor, and an inverter motor will maintain +/-1 RPM. VFDs have the advantage of electronic braking, this is more of an issue with the 1340GT that has no foot brake. With electronic braking you can stop the chuck in about a second, but day to day I use 3 seconds. This makes for very controllable acceleration and deceleration. Add an electronic stop and you can stop the carriage repeatably to an accuracy of better than 0.001".
4. You can do a fancy VFD system, or I have outlined in a previous thread of a simple conversion that you can do in a few hours and the machine will operate exactly like a stock 3 phase machine with the VFD variable speed and braking. It only requires a speed pot, an enclosure for the VFD and a braking resistor. You want to add more, this can be done later. You can have the electrician check out your high voltage wiring, but you are talking a very small nominal cost. A $1000 to install a VFD is a bit over the top, but the components can add up if you want to do a complete system replacement with all the bells and whistles. I both help people with this and on occasion build them. I would have pretty high expectations if you are going to shell out that amount.
http://www.hobby-machinist.com/thre...g-the-stock-control-board-and-switches.49022/
5. All this said, the 1440BV is a lot of lathe for the price, and basically being able to hook it up to power and have a purposely built VFD machine at this price level and capabilities is over the top. I do not know of a comparable factory VFD lathe that isn't twice the price. If going with this machine I would get better quality chucks and be done with it. Scope of work wise, I consider the 1340/1440 to be very close, so you are not missing something as far as what you can do on both machines. A slightly larger spindle bore, great if it comes with a machine, but not a huge difference in day to day use. Actually a 2" bore in this size machine in a rarity, and even larger more expensive machines do not have 2" bores. No big deal with a D1-4 vs. D1-5, the latter being a little less common and more expensive. I doubt you will find anybody that says it makes a difference in rigidity at this size level of lathe. The primary advantage is the accommodation of a larger spindle bore, and you need a larger chuck like an 8" to have a large enough through hole to get stock through the chuck.
So all in all, they are both great machines. One is more turnkey and you get a lot of bang for your buck, the other is a more honed/finish machine but will require the cost and time to upgrade to a VFD. Many of us went with the 1340GT because of the pleasure with using it, and that was important to us. But the 1440BV is a strong contender, and offers so much more than say a generic 1236 machine. They all are capable machines, so it is a difficult decision. There is also a wealth of information as to opinions and assistance at this site without getting flamed for asking.