Well my advice would be make sure its a premium diaper and that you are pointed up otherwise you are almost guaranteed of the bike wearing it,my personal choice is the northshore pror to it was Abena but in comparison to me the northshore front end just holds up better than Abena,and the front is what you will be relying on when most of the diaper is blocked from your weight on it agaist your seat, i would also suggest if you really love riding you look into getting an "Airhawk" seat these are replacement seats made by RoHo, RoHo sells these seats to the general riding public, this companys other lines are available by prescription only( as i write this from my wheelchair,i am supported and protected by my RoHo "quattro" seat cushion that my Doctor ordered,the " quattro" is the best cushion available from any company and was voted the #1 by Doctors and seating specialists around the world the last 7 years based on performance) Just last year RoHo was purchased by the #1 wheelchair company Permobil, you have to be really messed up in order to get insurance to cover a Permobil chair because as we say "Permo's do some sick tricks" but naturaly the cost of these trick's is high (the chair i'm in cost more than a full size Chevy luxury edition car, of course you cant drive a Chevy into Walmart but you can a Permo, you could try it but Walmart would not appreciate the new door you made and the Chevy would be totaled sitting in when you got out of prison for trying it)
But all jokes aside an "Airhawk" would be a great investment,alot nicer ride without the diaper,with the diaper there would also be some added give in the seat and therefor more absorbtion by the entire diaper not just the front that happens with a regular seat, if you want to look into it go to RoHo's site and you can then select Airhawk link rather than the various wheelchair stuff.
Let us know how it goes,and if you have any questions for my fountain of useless knowledge feel free to post or PM me i will be glad to aswer or help anyway i can.