Hi BG,

ICSI is more common because the chances of fertilisation are greatly improved.
BG
Have a quick look at this link:

100 Questions and Answers about ... - Google Book Search

it's all about getting the most viable embryo's each round. a lot of clinics now automatically use ICSI at no extra charge as the results are so much better.
BG
But is it the case that "nature" is selecting the most viable embryos using IVF as apposed to ICSI where the lab technician is randomly selecting and matching a sperm to the egg?

Regards