Remounting filesystems after enabling ACL's for NFS filesystems

I currently have a RHEL 5.4 server running as an NFS server. It exports 3 filesystems with the default option in /etc/fstab like this:

/dev/vg-LU99/LU99     /lu99      ext3    defaults        0 0
/dev/vg-U99/U99       /u99       ext3    defaults        0 0
/dev/vg-SYSADMIN/SYSADMIN   /sysadmin   ext3  defaults   0 0

I need to enable ACL's by changing "defaults" to "acl" and then remount.

I need to refresh these mounts on both the nfs server and about 50 clients without a reboot. If I understand correctly, I can run:

> mount -o remount /<mountpoint>

And this will allow the ACL support to the client. But I must also remount the filesystem on the client. I believe I can use the same command on the client for this.

However, these are production systems and downtime/reboots are not possible. I'm concerned about how filehandles and read/write operations are affected during and after the remount.  In particular, are they disrupted, cached. I'm hoping I can simply issue the command above without losing any read/write's. Can anyone help provide a little explaination or point me to the appropriate documentation?