replacing asphalt shingle roof vs applying sealent coating

The ice shield is sticky and glues it self to the wood serface . 
 Some you can peel up but some becomes a real sticky mess.
 Not only can you not peel the ice shield off the wood but it's a real job to get the shingles off also . 
 Some times we end up banging the ply wood off and replacing it . 
 In my area GP had a bad run of ply wood in the 70 and the stuff just rips up when you remove the shingles. 
 Gaf weather watch is good stuff . 
 Not to sticky , it has a granulate  surface so you could walk on it . 
 I think it's 55 bucks for 200 feet . 
 Grace makes the best  Products  but it is more then double the price.
i used ice and water shield on the  entire roof because I have 1x8 rough saw decking and did not want to get nail leaks
 because of  expansion and contraction of lumber , plus I am in a hi wind area .
 And yes the nail holes don't leak. 
  I really wanted a  Metal roof but it just cost too much money . 
  My guys shot my roof on for food and beer . 
 2 guys 2 days sun up to sun down 6000 plus feet .
 My son and I layed the plywood and ice shield  and my roofers just shot shingles.
 Steal would of taken weeks that I did not have.