On the 4th string combination...
Ok, so in my 4th string combination, I changed to an even lower tension (Pro's Pro: Nano Vendetta 1.25 @ 20 Kg on mains w/ Operation Twist 1.30 @ 19 Kg on Crosses) and stringbed response is now much better - improved power still with very good control, and very confortable (based on 1 hour session).
However, I found that for a OHBH it ends up being very very demanding stick, more so than 90 sq. rackets. If your timing is not absolutely perfect, the racket does not have sufficient weigth to still carry out the shot. With a 90 sq in. although it had smaller sweet spot the swingweight would compensate small timing issues, with the Mantis the lack of plough-through... (even weighted at 325+ grams) currently does not do any such compensation.
Well yes I do have to further improve my back-hand (which is not as bad as it sounds, it's decent) but I changed rackets because I was looking for some more help from the stick, and it's not looking very good at the moment.
Concerning power, you have to produce it yourself, so far the racket has not helped much on this department, but it might very well be from string choices. I'll give it a few more attempts here.
It's not all bad, I did gain the ability to better carve the serves, or flatten out serves. And at net it also seems a solid performer (more testing needed under pressure conditions).
Compared to say an Aeropro Storm in stock form, the big difference in power (ability to accelerate shots) was very very noticeable, but given the very similar specs, it has to be possible to produce the same level of power.
The biggest difference between the two were:
a) strings, the Aeropro used RPM Blast @ 24 Kg
b) Balance, the Aeropro Storm is 3 pts HL, and one could feel the slight weight in the racket head.
c) Mantis with 2g added 12 o'clock and 2g under butt.
Maybe I need to change that balance on the mantis and use a string with same qualities/properties as RPM Blast.
So, I'll have to keep tweaking to find the right spot for me.