External Hard Drive--use on iMac AND PC?

This is probably a dumb question, but here goes:

I will be using an EHD to backup some photos/videos. Can this EHD be shared by an iMac and a Windows PC with no problem? I know I will have to format it to exFAT to work with both. I'm just wondering if using the same drive between both the iMac and the PC would cause the drive to have problems, especially over time? I had planned to purchase two EHD's (one EHD for the iMac and one for the PC), but if I could get by with no problem with only one EHD and could save some money, that would be great.

Thanks in advance for any input.