Mine have cracked but are not leaking yet. I got them in May 2005 and they have been worn at least once a day if not twice and done a winter of knee deep mud.
To be fair I really don't look after them properly. I am sure if I did they'd last a lot longer.
I dont wear mine when it is real warm I wear my old ariat boots. But I do where them twice a day in lots of mud - and do lots of walking in them for at least 70% of the year. And they have done 2 winters!!
I know the Dubarry 'people' well and i've had mine for about 2 and half years,have not oiled them once (silly me) and they are ok looking with no tears etc where as a friend of mine has had hers 6 mths and hers have also split where the toes are,she rang the shop where Dubarry is and they told her that it's because she mucks out in them everyday and the ammonia rots the leather,i believe this is true.So if you want them to stay nice for a long time-don't muck out in them or enter your horses stable whilst wearing them.I know it's hard but it can be done.
No mine are fine. I think I've had them for 3 or 4 years and I've cleaned them about 3 times, have never oiled them. I reckon it's all the muck and poo and wee that keeps mine healthy looking