Help me to differentiate between Kenko 1.4x TC Models- MC4 DGX and Pro 300 DG

[Alokchitri]

Hello Friends

I came across the following two Kenko 1.4x Teleconverters:

1. Kenko Teleplus DG Pro 300 1.4X Teleconverter (Kenko Teleplus DG Pro 300 1.4X Teleconverter)

2. Kenko TelePlus MC4 AF 1.4X DGX Teleconverter (Kenko TelePlus MC4 AF 1.4X DGX Teleconverter for Nikon)

I intend to buy a 300 f4 AF-S Nikkor lens for my D90 with which I would like to use a 1.4x TC. After a lengthy discussion here and elsewhere, it seems that this combination will produce the sharpest IQ for least of the investment.

But I am not sure which of these two TCs is better optically. I found one German page which compared TCs and they declared the MC4 DGX is the best one. The DGX also costs about 40% less.

So please tell me:

1. Which of the above TCs will be better Optically with the lens I mentioned? What are/is the differences between these two TC models?

2. Are these Kenko TCs at par with the Nikon TC 14E II/14E? The Nikon's one will costs simply double of Kenko and also will not be useable with any Third Party Lenses, that much I am sure of.

Please help

Thank you