From what I have seen the Taiwanese Lotus bikes vary in quality much more than the Japanese Lotus bikes, even among the same production run. If you have a nicely made one, then it's probably a good bike. Like Frank said, Lotus used Taiwanese production to offer a bike at an even more competitive price.

If you buy a Japanese Lotus you are almost guaranteed quality construction, but be careful with the Taiwanese bikes.

I consider the Japanese Lotus bikes more collectable/valuable than the Taiwanese bikes, but that is just my personal opinion. I look at the Taiwanese Lotus bikes as a sub-class of Lotus, I wish Lotus had sold them with a different name. You can almost tell that Lotus introduced the Taiwanese bikes to meet a price point, not because they were great bikes.

Below is a photo of some very poor brazing on an earlier Taiwan Lotus Elite, note the crack on the fork crown point and the big glob of braze on the seat stay cap. I've never seen anything like that on a Japanese Lotus.