dual clutch sure will "experience" that?
will that be annoying?
will it disappear after sometimes?

Like what old1030 said, it is the nature of dual clutch, at least for the Fiesta powershift. I read that it is true for any DCT, including VW's.
Powershift transmission common sounds a driver may notice are:• Double clicking metal sounds. These noises can likely be heard while driving on very smooth surfaces during a 1-2 upshift or a 3-2-1coast down. The sounds occur with every gear engagement, but generally cannot be heard over the background engine, road and wind noises at higher speeds. Most noticeable if the windows are down and the radio is off, these sounds are of the shift forks moving and the synchronizers engaging a gear (similar to a manual transmission). These shifting sounds are part of normal operation.
• Coast down whine. A slight gear whine while slowing or coasting is normal.
• Clicking sounds after the engine is turned off. As the vehicle is powered down, the transmission will cycle the clutches to the released position so it is ready for a safe restart of the engine. This is part of normal operation. Clicking sounds from the transmission immediately after the engine is turned off are normal.
• Low speed grinding. A slight grinding noise may be heard at about 2 MPH. This noise is more evident during “trailer-hitching” events (see below). This noise is caused by a normal bearing rotation and does not affect the durability of the transmission.
• Reverse gear whine. Some PowerShift transmissions will exhibit gear whine in reverse. The level of whine has been significantly reduced in later build vehicles, but can still be detected to some level. This is characteristic of many manual transmissions, and is not a defect or a situation in which a repair should be attempted.
• Trailer-hitching feel. Some customers may experience a trailer-hitching feel (or a slight bumping feel). The trailer-hitching feel may occur in lower forward gears – particularly if the customer is off and on the throttle quickly. It may be more noticeably in a parking lot or when a customer is doing multiple on/off throttle pedal maneuvers. This trailer-hitching/engagement feel is a normal characteristic of the dry clutch-equipped manual transmission design. Conversely, conventional automatic transmissions are equipped with a torque converter. The torque converter is a fluid coupling device which dampens these positive engagements feels.
Source : www.fordtechservice.dealerconnection.com ,
http://www.ivancheam.com/blog/6-speed-powe...haracteristics/