The main lock is only designed to immobalize the rear wheel and will not prevent someone from carrying the bike off. None I know of are designed for front wheel mounting. The Axa optional chain should raise the security level significantly if properly used IMO but also ups the weight carried and use hassle.

Used with the chain it is probably an improvement over most cable locks up to 12mm or so in diameter but they provide minimal protection based on posts I have seen here.

I agree with wahoonc as to the difficulty of accessing the locking bar for cutting. My bike with it mounted also has a rear rack installed, making access to the lock even more difficult.

Certainly going to slow a thief down but there is always the risk of some idiot not noticing the lock and damaging the rear wheel if they try to ride off with the lock engaged.