I have made EG's from the day it came out and never had one fail, break or else. I don't use a press block, I assemble carefully with an arbor press. My recommendation is to use a de-burring tool and make sure no glue or other crap is in the brass tubes before assembly.
One of my colleagues has one of my EG's and here only the gold on the clip has worn off (Upgrade Gold, not TiAu)- but he uses it as his daily writer for four or even five years. I offered him replacement for free, but he likes this pen so much (light, right size etc plus now a nice patina) that he refused.
Personally, I use an El Grande Streamlined FP for several years now and still have my very first EG (RB) and they are both fine.
I have no experience with the Churchill, I don't make this model.
For warranty, I pretty much do the same as Lou - and so far had to replace only one pen. This was a Baron with a double celtic knot in blood wood and maple (and yes, the blood wood on this as well as three or four more pens failed and cracked - the wood was stored for years in form of pen blanks in my basement) - this pen I replaced with a DCK Baron in IBO and Holly. The customer was very pleased with this free exchange (and upgrade with IBO), so he bought more pens from me.
I have, however, repaired my share of pens, mostly FT Americans. Some people do put pens in their pant pockets (why I don't know, for me this is not the smartest place to carry a pen), or worse in the back pockets and then sat down, breaking the transmission. Easy fix, though.