Purely my own 'personal' view here.
Check my profile for photos & write up. I had FUE HT with Dr Karadeniz & team 4 months ago.
Talk to him via email; phone; Skype before making a decision. But remember... HE is the surgeon (& 90% of the time HE will be 'hands on' with the procedure, NOT anyone else). Longevita is merely an Agent/middleman for MANY practitioners.
If you have concerns with using an agent, then deal 'directly' with the surgeon.
But (& again I can only speak for myself ), MY EXPERIENCE of this surgeon (& a great team ) was VERY POSITIVE.
Good Luck with your final decision, 'I know' it's not easy & the consequences of it going wrong are traumatic.