others may consider social hub as bloatware, but for me its the best email application. push mail for my hotmail n gmail, personal or company mail. its the only hub i using, others all frozen using TB pro 
are u using digi as well? then only can compare. i also notice that the network signal hardly maintain at H+ when i didn't surf the net, but when using the internet actively it will remain at H+. i believe its a way of  conserving ur battery life though. anyway r u using stock rom and which modem version r u using? give more information so that we can provide some opinion 

settings -> about -> baseband

i duno bout MIUI but basically networking shud be using the same principle. edge and 2G is using the gsm network for data sending and receiving, which is the same network with our cellular network. thus, when we using the gsm network to make call/ send sms, data will stop temporary. if we are sending/receiving data, others can't call in. correct me if i'm wrong but i dun think i'm wrong 

Thanks for clearing that up man.

Guys... *deep breath*

GSM/EDGE DOES NOT SUPPORT SIMULTANEOUS DATA AND VOICE.

Go google. It either drops ACTIVE data when calls come in, or holds ACTIVE data and drops calls (depending on the mode it's running on).

E being displayed on the status bar and whatsapp running (for instance) DOES NOT MEAN IT'S DOWNLOADING/UPLOADING ALL THE TIME.

To try, download something big on EDGE. Then call yourself. Voila.

ONLY WCDMA and above (HSPA) supports simultaneous data and voice. Oh, and WIFI obviously.

As a solution to the jumping issue, try this: type *#301279# in the dialer, select HSPA revision, and select no 2. Now press on your menu button and select END. Lastly, turn flightmode on and off to refresh.

Now HSUPA is off, and it jumps less. You WILL NEVER EVER SEE H OR H+ in the status bar any more (as HSUPA - the upload part - has been turned off), but download speeds shouldn't be effected by much (HSDPA is still on), EVEN if it ONLY shows 3G.

To return to your normal config, redo the whole thing but select number 3 in HSPA revision menu. Or you can go hardcore 3G only and select 1 to turn off both HSDPA and HSUPA off.

Have fun.