it'd be interesting to see if the car did actually have more grip though, or if it just felt nicer meaning you feel more confident to push it that bit further.
I had an old astra with stock suspension and some decent sticky tyres. it gripped like **** to a blanket but felt horrible. I eventaully fitted some Konis and lowered it around 50mm, and it no longer felt horrible, but its limit of grip was still in exactly the same place. Ok it felt nicer and was more chuckable on backroads, but it didnt actually grip any more.
I suspect that you may find your car feels nicer, but the negative impact of overstiff ARB's would mean that under certain conditions (lets say hitting a pothole or dip half way round a corner) your car could lose grip due to the ARB that it would otherwise not have lost.
Its the same story with people who lower their hatches into the weeds then inform you with great conviction that it handles "on rails". The only issue being that their suspension geometry is now completely humped so that only half the tyre is actually in contact with the road, and theres no travel left in the suspension so that when it does acutally get driven properly it simply wont handle as well as it could.
Also if its starting to crack subframes due to the stiffness of the ARB, you know theres something wrong!