Call me crazy but I am using a 10-year old laptop (original centrino 1.4 single core processor with 2Gb ram) and the thing flies because I have a light Archlinux running and only what I need on it. Can boot to Window manager in 8 seconds - beat that MS Windows XP/7/8.. By the same token, I am also very happy with the pulse and it runs just what I need. There is something very satisfying about getting old hardware to run more efficiently than new machines. OK, so I have to wait 7 seconds for whatsapp to start on the pulse but that's another story - its not my fault that everyone has chosen to use whatsapp instead of better, faster alternatives (the same way VHS was chosen over beta max - now I am showing my age).
I was scared too at the beginning of bricking my phone. I wrote at length in this forum somewhere about what I did to recover from that.. But honestly, in my experience its virtually impossible to brick the pulse and that's why I love it, because its such a good phone for flashing, testing, learning etc.
First, do you mean that you have a /system partition that is 220Mb?? Are you sure? Mine (that came with my flashed Ecuador Movistar 1.5 android rom) is 85Mb. Everyone on this forum talks of TRE/UK/Hungarian roms giving you 110Mb but that breaks the 3G frequency for Ecuador so I am stuck with 85mb.
I really see no good reason to go to a 2.1 rom but if you want to try it, put time machine update.zip in the root of your sdcard. (make sure you copy off everything important from the SDCARD first) and there is no emergency that your phone must work for a few hours before trying this. Then pull the battery and run the update sequence (holding down Menu+End(red button)+vol up, slide the battery in) and it should flash the update.zip. I find the movistar 1.5 rom can also be used and you can use that update.zip which will then allow you to flash 2.1 or 2.2. From there you can flash 2.3 if you wish. I really find the Styx rom very good and fast.
I am just re-reading your message and it sounds like you are doing everything correctly. YES, you are correct, you will need to use time machine or movistar 1.5 rom to take you back to earlier Android versions.
Once you have re-installed, the most useful program I have found for monitoring battery use is 'system panel app/task manager' Note you only get the graphs if you buy it but its worth it (graphs even work on 2.2, unlike batterbattery stats app). It will show you exactly what is using the processor at which time. Let me know if you have trouble finding suitable Time machines/Movistar rom and I can find and upload them for you. Cpu tuner is also very good if you want to for example switch to use only 2g only when the phone screen is off and fancy things like that which will help you save more battery.
I am writing this from memory but write back if you get stuck and I will help you become unstuck. Good luck!
EDIT: btw, Desalesouche, not me is providing new kernels and patches, I've just done a lot of testing
Edited by pedrojaime, 26 March 2013 - 04:01 PM.