Resale value is not going to be affected by the lack of tub. It will play a role on how attractive your place will look to potential buyers. My advice to you is to keep the tub and say no to tub sliding doors. A shower rod with an attractive curtain is a sure way to get a much better bang for your buck and still have a bathroom that looks great and fresh.
I have done dozens of bathroom renovations. From complete rehab to just a few simple changes to make the space more attractive. If you need a hand, please let me know. I will be happy to assist.
Good luck on your project.
It looks really nice and friends have loved it....
Also, consider long and hard before you install the stall type of shower (the sliding door) on your existing tub. In my experience, this is one of the first things buyers want to get rid of.