I'm a newbie to Tibolone, just started my 3rd month, hysterectomy saving ovaries 1999 but ovarian failure soon after but last year a scan couldn't find ovaries and the sonographer reported that she's convinced they've dissolved and gone.  I think my gp and gynae must've agreed too
So been on oestrogen only hrt and have struggled badly since 2012.  Like you I cannot tolerate any oestrogen above 50mcg comfortably 
Pros I've noticed these 2 months :
Sexual response better
Hair more manageable
Better mood
Social anxiety a little improved
Bowels better
CONS:
weight gain (@5llb)
Sore vagina externally despite using Sylk and vagifem
Not getting to sleep easily so now I take one phernergan tablet every other night 
There are some common settling in symptoms like jelly legs, dizziness etc but fortunately I didn't get them.  I had a hangover feeling each morning for the first 3 weeks
I'd always say it's worth trying.  I have always taken the whole 2.5mg tablet but if you're worried maybe break it in half and settle in that way.
There's Tibolone threads and Suzanne tells a very honest detailed journey on it, she's doing so well
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