The main snags in postal voting that I envisage are twofold:

1) Delivery of ballot papers to the voter. Post Office loses an astonishing amount of mail en route, and houses in multiple occupancy present a particular problem.

2) Voting needs to be done ahead of poll day. This means that information/persuasion in the last few days is unlikely to be taken into account.

As neither of the above will skew matters in a party political sense (all parties being equally disadvantaged) and the turnout is generally held to be more likely to increase under an all-postal system I think that on balance it is probably a good idea.

I have had a postal vote myself, by choice, for some time. It certainly helps for those who work far from home, or odd hours.