I can only speak for the Softbits products - I've had a half roof almost since they first came out,and apart from re-proofing after using their cleaner on it, have not had to do any maintenance. and it works well in all but the most extreme weather. I've coupled it with their draught screen which helps keep out rain blown in from behind and reduces headlight glare as well as substantially cutting buffeting.
The shower cap has also stood the test of all kinds of weather, although I would advise you to put the half roof up underneath it if you are expecting heavy rain or snow to give it some extra support. It also has the added bonus of keeping the dust out (LE0 is parked under a flying freehold) and also animals like foxes or cats (!)
Despite being an 03 plate, LE0 has 109,000 miles on the clock, and is driven 365 days a year, which should indicate how much use the two covers have had.
Edited by - Anton on 20 Dec 2013 01:23:34