Personally, I do not like the Alien Gear products in general or the ShapeShift system in particular. However, this is not from personal experience, but rather from serious research. This just means Alien Gear is not right for me or mine. It may be right for you. Only you can tell.
A co-worker of mine, who has carried for less than a year and has not taken training yet, has the ShapeShift and likes it. Alien Gear has a YouTube channel with videos. https://www.youtube.com/user/AlienGearHolsters
For a different view, John Correia, of Active Self Protection, has a video discussing the Alien Gear ShapeShift.
John also has videos discussing the qualities of a good holster.
My 22 year old son carries his S&W M&P M2.0 Compact 9mm 4inch in a Bravo Concealment IWB holster.
My youngest brother carries his S&W M&P M2.0 Shield 9mm in a Raven Concealment IWB holster.
My 86 year old father carries his S&W M&P M2.0 Compact 9mm 4inch in a Safariland OWB 7TS ALS holster.
I carry my S&W M&P M2.0 9mm 5inch openly in a Safariland OWB 7TS ALS holster for both EDC and pistol competitions.
Two of the instructors I know well and can highly recommend carry their S&W M&P M2.0 Compact 9mm 4inch in Raven Concealment Morrigan IWB holsters. They use the Morrigan in USPSA matches. One is a Grand Master and the other is a Master in USPSA.
In carrying a handgun and choosing gear, it comes down to which risks we are willing to manage and which benefits matter most to us.
Have fun, be safe, and carry.