It would replace bitlocker, yes.  Hardware encryption used to be less hardware intensive than software (i.e., Bitlocker).  That's generally no longer the case.  Bitlocker can be centrally managed more easily than full disc encryption (hardware), but they achieve the same goals. Either way, be sure you have a secure backup of your encryption key (it will be backed up in your Microsoft account for Bitlocker if you have activated Windows with a Microsoft account;  if not, you MUST keep an off-system backup of the encryption key.  If you're using FDE, make and keep a backup of the key/passphrase. Loss of the backup key means irretrievable loss of the data on the drive in either case.  
Dell seems to have it's own encryption driver, for high end computers like mines, does it replace Bitlocker, which is enabled on my laptop? If this driver works better and is more secure then I will install this one over bitlocker.
DELL Data Encryption vs Windows Bitlocker