To be honest, my personal opinion on this is that they are a hard trance act more than anything. OK, they do drop the occasional 'hardstyle' tune, but even then it's very much on the hard trance end of the hardstyle spectrum.
What annoys me, and tbh it's not really their fault, and has more to do with Nukleuz's publicity machine latching onto a name they believe is becoming a cool tag, is that they are regularly publicised as a hardstyle act, and to me that is just giving hardstyle a bad name and leading to the misconception that hardstyle is basically just a new tag for hard trance.
This runs right up to the level of other promoters I have spoken to, mentioning no names, who talk about booking the pair to play at their hardstyle nights as a headliner. Sorry, but thats just bollocks, as I say their a hard trance act more than anything imo, and headlining hardstyle nights, putting tunes out on Nukleuz that are blatant attempts at hardstyle etc, to me is a major cause of people misconstrueing what hardstyle is and for me is a barrier to many people taking an interest in hardstyle i.e. they believe it is purely hard trance by another name.
That is my experience from talking to people on the scene anyway. I have lost count of the number of people (mainly in the techno and hardcore scenes) who have told me hardstyle is shit, and its just trancey bollocks, for me to sit there trying to tell them other wise, but when all they have heard is the likes of Cally & Juice and Yoji Biomehanika then it is always going to be an uphill struggle.
Fair enough this is offset by the fact this end of the hardstyle spectrum appeals to the massive hard house and hard trance market, but getting this crowd interested in the music to me is only worthwhile if it doesn't involve devaluing the music for those who are already into the sound.
If, as you say, they themselves regard themselves as a hard dance act more than anything, then they should stop producing tracks with names like 'UK Hardstyle' that further this misconception, and Bionic should stop promoting themselves as the UK's biggest hardstyle night, and arguing that Cally & Juice are a hardstyle act when they are pulled up on the subject of the distinct lack of hardstyle on the line-up.
Saying that, to be fair, it's not so much Bionic saying this as the masses of their fans on other forums who come out with such bollocks.