I would rather keep all my old memories. I've lost many family members and friends and would want to keep the memories of them in my mind and heart.
I'm not sure, and I really can't think straight, to excited about Facebook being hacked. However, I can think of several memories that I would prefer not to have, but not all of them, too many valuable leasons, even in the memories I don't like... Okay, I go for option number three, not to lose any of my memories and still have the ability to make new ones.
You Do Not Have A Choice. All Are Bound to "the Wheel of Eternity" (continuous "life-death" Cycles). Each Directional Passage (into "life" or into "death" etc.) is Through "The VEIL-Of-The-VOID," which Wipes Clean All Memories (it is also refered to as the 'Veil of Forgetting'). Once on the Other Side of the Veil, memories fade, but never instantly, and these are of much Help,,, like Unto Waking From A Dream. ... In Truth, EveryThing is Permanently Recorded In The Dual Soul~Spirit Star, and When You Evolve Further, All Memories Are Seen At Will.
I don't Indulge in Such. Many experience both Your 'hypothetical' scenarios, generally due to illness or injury. I experienced both aspects due to a loved-one's illness, who eventually recovered. It was nightmarish for me, as well. When they recovered, not all old memories were available anymore, and new ones became possible again.
Can I have some of, whatever it is you're on?
No... It'd Burn Out the little wire you call "your sentience," and You'd be worse off than you are now. Re-Apply after 100 more lifetimes experience (someone may be able to help). Duh.
In my case, it depends.. if my old memories are very very good or very very bad. =p
As it happens, nature is making this decision for me...the memories of my decadent past are as clear and vivid as if they happened yesterday, and my short-term memory sucks, so---
Hope I'd never have to choose :/
Losing old memories would mean losing my son for good so I'd choose the not making new ones .