the price is same element & rs online

I saw the price at RS is about $42 (RM128) while element14 is RM111.

Same as RM 111 what.
http://malaysia.rs-online.com/web/p/products/7568308/?

that's uk price ler

Almost 1 million Pis sold since February 2012 > Link

(how do you spell the plural of Pi? Pis?)

Feeding back power is a common thing for some hubs.
And yes if you have the old PI (the one without mounting holes) then only powering the PI by backfeeding it will be a problem, as the PI will only partially work, and there is a small chance the content of the SD-card may get corrupted. But if you feed the PI both by backfeeding AND by frontfeeding it, no problem exists, many people with the old version are doing this. And yes, this gives a "loop", but in practice 99.9% of the current enters from the front, and the "loop" isn't a problem at all.

If you have the new Rev2 version of the PI (the one with mounting holes) its safe to backfeed it alone!
That was one of the improvements of rev2.

I have this issue from my 2nd Pi. Only this Pi behaves like this.

Sometimes when I pull anything out from the USB slot (wireless adapter, keyboard/mouse), this Pi automagically reboots. Meaning, it actually lost power and then powered up.

I'm 100% sure there are enough power into the Pi bcos I'm using the adapter for iPad 5V/2100mAH. VERY annoying when I'm coding.

Anyone else?

I have this issue from my 2nd Pi. Only this Pi behaves like this.

Sometimes when I pull anything out from the USB slot (wireless adapter, keyboard/mouse), this Pi automagically reboots. Meaning, it actually lost power and then powered up.

I'm 100% sure there are enough power into the Pi bcos I'm using the adapter for iPad 5V/2100mAH. VERY annoying when I'm coding.

Anyone else?

Don't hot plug USB devices directly into the PI, if you must hot plug plug into a hub instead!

Its called "the rush in current problem", and it makes that the current PI itself is non "hot pluggable", note that the revision 1 PI was hot pluggable, as the two polyfuses prevented any rush in current because the fuses had a non zero resistance. But in the current board there is literally zero resistance between the PI's 5V supply, and any USB device you plug in, that means that if you plug in any USB device with empty power decouplers, (which act as a complete short for a very small time) then you are actually simply shorting the 5V when you plug de USB device in.

The polyfuses in the revision 1 board however caused much greater problems than this problem, and for that reason have been removed.
Its possible and likely the hot-plug problem will be solved in a (final?) redesign of the PI by placing tiny resistors (smaller than 1 Ohm) back in the power path to the USB device.
However, if you have an USB hub plugged into the PI, its normally protected against the rush-in current so you can safely plug in an USB device into the hub.
As the current PI only has two ports normally there is no need/possibility to hot plug anything in anyway, (without a hub) as the two ports are reserved for a mouse and a keyboard, unless you want to hot plug the keyboard. If you want to plug anything in beyond that you would already use a hub, and as said, you can hot plug safely into a hub.

Well, i used to have this issue previously but it happens when i plug in something.
Yeah very annoying when coding. But after few googling.. found out its because of
the resettable fuse (polyfuse).

So, its recommended to use a usb hub connected to the usb port on the pi instead of
directly connecting it (for hot pluggable devices)

sort of right with the polyfuse but then again, maybe some usb hubs protect the current surge but this rm 15 hub i have does not. i first experienced it when plugging to the hub. i tot my hub faulty. then plug to usb port directly. same same.  . decided to contact element14 for RMA. hopefully they comply.

are there any confirmed working powered hub that is confirm working for rpi (prefer less fault, less reset)

even though i m using a powered hub, my house there sometime got minor power surge/spike, changes in power voltage.

so far i dont plan to get voltage regulator...  not sure if anyone  facing this issue?

are there any confirmed working powered hub that is confirm working for rpi (prefer less fault, less reset)

even though i m using a powered hub, my house there sometime got minor power surge/spike, changes in power voltage.

so far i dont plan to get voltage regulator...  not sure if anyone  facing this issue?

i am not sure about the others, but vztech 7 port one worked just nice for me.

I am using this powered hub also.

i have a ATEN 4 port hub that I can power using 5v 1A. that one is ok.

my other VZTECH 4 port hub that also can be powered is not ok.

cheap and good..