I don't think Pools price is overly attractive. Their away performances has been very poor (despite results) since around March. Their home performances are completely different, I'd much rather bet them -1.5/1.75 at home to United than -0.5 away.
This season is a lucky win away to Sheffield courtesy of a Henderson blunder, they were average that game, draw was probably fair. Similar performance against Chelsea, also think a draw would be fair. They weren't playing well against Burnley until Trent scored from a cross. Were fortunate against Southampton also, wasn't a great performance and should have went 2-2 with a late sitter. Back to last season, they just managed to beat Newcastle. Was the Cardiff game where the guy missed a sitter then had a blunder to gift pool a goal. Game before that was the Southampton game where I think Pool equaliser was offside when they were playing badly? Then the Fulham game before was the Rico error late on for a pen. Can't remember the games prior to that. Essentially their away results are vastly superior to the actual performances that they are putting in. Pretty sure their previous two visits to Old Trafford came during bad form for United as well didn't they? Have a vague memory of people expecting Pool to win easily. Last season they were terrible at OT despite United having 4 injuries in the first 30 and Rashford struggling to run the entire game.
I guess you could say that Pool's results in spite of performances are a sign of how good they are but if you take their betting lines at kick off for these games then they Won v Chelsea, burnley, half loss v Sheffield United, half loss v Southampton, loss v Newcastle, refund v Cardiff, win v Saints, loss v Fulham. They've not outperformed their handicap by more than half a goal in any of these games bar Burnley.
This all being said, I wouldn't be betting United either. Price is probably about fair for me.