From my experiance id say for the price you cant go wrong nfor the 400, this is becasue the dx6i is worth the deal alone and you get a heli for free.

Now i have had my fair share of problems with eflite stock parts but choose to go down the upgrade route almost straight away. I went cnc throughout ( tail, head, body etc ) but these were not due to eflite parts failing just so it became more crash resistant.

The eflite esc has failed twice on me now so i swapped that for a emax esc instead and sinse had no problems since + i can now program the esc to do all sorts which is nice.

I swapped all the servos for hitec 65 mg`s. The reason i swapped these though was the first " real good crash" i had wiped all the stock servos out and again decided to go metal for durability. I would be one of the first to say the eflite servos are little more than junk, but when you compare the price, they have to skimp on certail luxuries to keep the price down.

Im buying a new heli a 450 kit on friday and custom making my own now as ive found i can have it my own way with parts i prefer to get a much tighter bird than just buying a rtf.

As far as rtf helis go, yes the blade could be better but for the price dont put your expectations too high, you get what you pay for as the saying goes