[Samsung Epic 4G Touch] b1g.p0ppa:
Yups, I can attest if you f*ck it up your phone will not boot. But, it isn't gonna brick ya, just pull the battery, boot to download mode and flash EL26 then re-flash the cache wipe, the ROM twice, and gapps like normal.

*Sigh* I'm prolly gonna regret this but here goes. FOLLOW THESE STEPS AT YOUR OWN RISK--NOT MY FAULT IF IT DOESN'T WORK FOR YOU:

Here's a buttt-ugly script I wrote to make sure we're not gonna create duplicate entries in the /system/build.prop. Has to be run from adb shell as root and clearly there are some hard-coded paths so either pretty it up yourself, or create a folder called /sdcard/gscript and make two files:

/sdcard/gscript/tweaks.build.prop:

########### b1g.p0ppa tweaks ##################################

debug.performance.tuning=1

debug.sf.hw=1

media.stagefright.enable-http=true

media.stagefright.enable-meta=false

media.stagefright.enable-player=false

media.stagefright.enable-rtsp=false

media.stagefright.enable-scan=false

mot.proximity.delay=25

net.tcp.buffersize.default=4096,87380,256960,4096, 16384,256960

net.tcp.buffersize.edge=4096,87380,256960,4096,163 84,256960

net.tcp.buffersize.gprs=4096,87380,256960,4096,163 84,256960

net.tcp.buffersize.umts=4096,87380,256960,4096,163 84,256960

net.tcp.buffersize.wifi=4096,87380,256960,4096,163 84,256960

net.tcp.buffersize.wimax=4096,87380,256960,4096,163 84,256960

persist.adb.notify=0

persist.service.usb.hubport=4

persist.sys.purgeable_assets=1

persist.sys.use_dithering=0

pm.sleep_mode=1

ro.com.android.dataroaming=true

ro.HOME_APP_ADJ=1

ro.lge.proximity.delay=25

ro.media.dec.jpeg.memcap=8000000

ro.media.enc.hprof.vid.bps=8000000

ro.media.enc.jpeg.quality=100

ro.ril.disable.power.collapse=0

ro.telephony.call_ring.delay=0

video.accelerate.hw=1

windowsmgr.max_events_per_sec=250

ro.ril.hsxpa=2

ro.ril.gprsclass=10

ro.ril.hep=1

ro.ril.enable.dtm=0

ro.ril.hsdpa.category=26

ro.ril.enable.a53=1

ro.ril.enable.3g.prefix=1

ro.ril.htcmaskw1.bitmask=4294967295

ro.ril.htcmaskw1=14449

ro.ril.hsupa.category=6

########### b1g.p0ppa tweaks ##################################

and then a /sdcard/gscript/tweak_build.prop :

#########################################################

mv /system/build.prop /system/build.prop.orig

rm /system/build.prop.linestodelete 2>/dev/null

for i in `awk -F= '{print $1}' /sdcard/gscript/tweaks.build.prop`; do grep $i /system/build.prop.orig >> /system/build.prop.linestodelete; done

CMD="sed -e "

for i in `awk -F= '{print $1}' /system/build.prop.linestodelete`

do

CMD="$CMD/$i/d;"

done

CMD="$CMD /system/build.prop.orig"

echo $CMD

$CMD > /system/build.prop

cat /sdcard/gscript/tweaks.build.prop >> /system/build.prop

chmod 644 /system/build.prop

rm /system/build.prop.linestodelete 2>/dev/null

#########################################################

Then in adb shell as root type:

busybox mount -o remount,rw /system && sh /sdcard/gscript/tweak_build.prop

Then reboot your phone. Go into root explorer if you want to double-check your new /system/build.prop first.

Phew, now that that's over with, Ima go flash Codename-Android-(MOD)-2-04182012-NIGHTLY-E4GT.zip right now!!!!!! Then I'll do the exact same thing above cuz you get a new build.prop with each ROM.

EDIT: Oooo, nice new flashing animation, Erick!

Sweet: kernel = FD16