People are going to say it depends on your style..
If you rely heavily on smashes to win points, like you can only win by smashing. You should probably use the Z slash.
If you play offensively, smash a lot but also like to clear and do other shots the Z force is for you. It is also good for smashing, I would recommend the Z force even if you can only win by smashing. But you should try both rackets.
I-slash is less stiffer than Z-slash . and i seem to feel a little bit head heavy for z-slash . therefore z-slash will perform better in attacking play such as smashing . and i-slash will perform better in control and net play . hope this will help you
I am also interested in comparing the frame durability between z-slash and i-slash. Any input will be much appreciated
i cannot comment on the durability because i've not broken either of racquets i've ever owned
but by theory you can probably figure out that the Z-slash is more "brittle" than the I-slash because the Z-slash uses high modulus graphite at some parts, whilst the I-slash doesnt contain any high modulus graphite at all.
i wrote a short comparison of both racquets recently in another forum subsection so if you could be interested it can be useful to help you decide whether these racquets are for you