Echo has a lot of options for heads, depends on what you are looking for - bump feed, easy load, speed feed, they even have maxi-cut (plastic flail blades)
We've never yet seen any sort of problem with the Quick Load head (pre-cut strings) - they did have a problem a few years back before Echo bought out the manufacturer (Kwik) where the pawls were not gripping the lines (there's a pawl repair kit available) so if they had a problem with that machine and it was less than 5 years old they should have taken it to an Echo dealer and gotten it fixed under warranty... the trimmer head is covered as well.
We actually have a customer that is well known for beating the crap out of his equipment.. commercial user, mows cemetery lawns, I believe 6 or 7 a week... he used to go through a new Weedeater from Wal-mart every year, if not more frequently... he used to use stihl, went through one every couple years, started using Weedeater (and Homelite and Husqvarna) when Stihls got too expensive...
3 years ago he got an Echo GT-225.. we put a bump feed head (I think it was a U-Turn head) , and still has not managed to kill that machine.. only been in twice for service - once for a tune up, and once with a rusted and broken i-Start damper spring. Suffice to say he is amazed with the durability of Echo.. and if and when he ever kills this one, I know without a doubt he's gonna buy another.

How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)