I played on a N52 (original, not "te") for years. When the G13 came out, I bought it immediately.

Let's just say that would my G13 break down, I would not even bother taking the N52 back up from the basement, I would just refrain from playing until I have a new G13. it is that good.

More keys make a BIG difference to me. The thumb stick is great (I had my doubts about it before my purchase, just from seeing pictures). The keys themselves feel like high quality keyboard stuff (much better than the N52 that always felt rather cheap). The hand position is much more comfortable. Etc, etc...

Software is pretty similar in functionalities on both products (still talking about original N52 here, I don't know the N52te).

I find the LCD display useless, and the G1 key (top left one) is not the easiest to reach, but that not enough to really complain about anything.

My advice : go for the G13, it is a great product.