I am not familiar with PXE server but standard feature set provides all the Loadbalancing features. Enhanced feature set is used for GSLB (global load balancing),Nat Peering and strong encryption.

From release notes

"The Enhanced feature set contains all of the Standard feature set and

also includes Network Address Translation (NAT) Peering, Domain Name Service

(DNS), Demand-Based Content Replication (Dynamic Hot Content Overflow),

Content Staging and Replication, and Network Proximity DNS. Proximity

Database and Secure Management, which includes Secure Shell Host and SSL

strong encryption for the Device Management software, are optional features."

Syed