First of all, IG's were not made in Taiwan. Originally, they were made in Hong Kong then manufacturing was transferred to mainland China, from about 1990 they were built in She Kau.
The early Chinese examples were not well received, I understand the production quality improved, but can't really help you in regard to the post 2000 boats.
In the early days Halvorsen was actively involved with the manufacturer of IG's, as time moved on production was farmed out, which did cause some issues in regard to quality control
When you say the 39' model, are you referring to the 40' Sedan/Europa style?
Here is a not so complimentary boat review by David Pascoe on a IG 40' Europa from the early 1990's
Boat Review by David Pascoe - Island Gypsy 40