G42 IS GREAT CHOICE..three suggestions
1. Disassemble and polish ramp to mirror....mothers or equal
2.  During breakin use lots of lube..froglube or equal
3. For CCW use Hornady CD Ftx....the cone shape feed real good
And they have more pep for action cycle
4. For reloads use higher grain loads

2% stoppage rate is better than mine.

Don't touch the feedramp.  It has nothing to do with FTE and a Glock doesn't require it to run right.  Was the failure a FTEx or a FTEj?

I bought the first one out of my LGS and I have shot about 500 rounds out of it including two GSSF matches and two fun matches at my local club. It ran 100% in any brass cased I tried as well as freedom munitions reloads. My buddy has one as well and he has shot it the same amount or pretty close.

Steel cased it's a whole nother story, shit won't run for shit.

Surprisingly steel cased (tula) is the only thing that runs in mine so far.

I'd write it off to ammo or operator and see if the problem continues.

G42 needs full power ammo. I had some reloads which work in Sig 230 but never extract in 42. I have no hangouts with factory ammo at all

Define full power. How when buying factory ammo do I tell the difference?

Mine likes Tula but hates Winchester, Remington, Hornady and HPR.

Mine runs great with Fiocchi and AE.

Herters is not full power.  Says 800 fps on the box.  It would not eject in my 42 but would in my LCP

 

Maybe we got lucky or others were unlucky, but ours works with all the brass ammo (never tried steel) we have put in it. After reading the "I got a lemon post" I decided not to do anything to ours out of the box, wiped off the Glock grease and shot 200 hundred rounds thru it with 100% success. Took it home cleaned, polished and lubed and it of course it was 100% every time we have shot it. We have an LCP also and it has never had a FTE or other malfunction, but there is no comparison in the two as far as accuracy and pleasure to shoot, once again Glock wins at our house.

Odd are in the buyers favor. In the long term Glock talk 42 thread only 27% of Glock 42 owners are experiancing problems. Based on that you have a 73% chance of getting one that works.

Plus everyone accepts a different amount of stoppages as acceptable. To some one stoppage per box of ammo is acceptable. To some one stoppage per 100 rounds is acceptable. To others 1:1000 is the minimum accceptable stand.

I love mine. both my 11 and 12 year old love to shoot it as well.

It's a relative term (otherwise somewhat meaningless), but in the context of the G42 what "full power" is referring to is a loading that generates at least 200 lbs of energy at the muzzle (4"brl.).  This doesn't translate directly to feet per sec., but in general will usually mean a loading that reaches at least 950fps from a 4" barrel.
Some loads that are very close to the 200 lb. threshold are: UMC/Rem 95gr., Winnie White Box 95gr.  Fiocchi's 90gr. JHP is right about at that power level with a fps of about 1,000fps (4").  There are many others.  

It's worth owning a copy of this:
Ammo & Ballistics 5: Ballistic Data out to 1,000 Yards for over 190 Calibers and over 2,600 Different Loads, Includes Data on All Factory Centerfire and Rimfire Cartridges for All Rifles and Handguns

It's a pretty handy reference and will help you sum up almost every commercially loaded cartridge out there.

Interestingly, the "hottest" .380ACP loadings (such as some of the Buffalo Bore brand cartridges) are turning out to be a little bit too energetic for reliable use in the G42.  With those, the G42 will sometimes lock the slide back on a still loaded magazine.