am planning to combined eight CAS & HUB Servers together in front of Hardware Load Balancer, is it better to combined them or no?

Please see: Understanding Multiple Server Role Configurations in Capacity Planning and Roberts Rules of Exchange: Multi-Role Servers and Patching the Multi-Role Server DAG Note also that you can not use Windows NLB combined with the clustering on DAG nodes. If you want to load balance the CAS role, you will have to use a hardware or another software load balancer

Thanks all for the reply, what am looking for is the best performance, i have read too many article that got me confused, some are saying the HLB cannot be used to load balance SMTP traffic other say its supported. my environment will be fully virtualized so i though i'll scale-out by combining the HUB & CAS to minimize the number of server, while i was calculating the number of servers i need, i found that i will need 8 CAS Servers and 4 HUB Servers so do u recommend to combine them or single role deployment will be better? and HLB can be used with SMTP traffic or for HTTPS traffic only?