That sounds good.

Sizing of the system is more then just ram. There are some items that need to be considered. Your 11 small databases may not be an issue. You want 100% of database size memory in SQL if you can get it. The 128Gb is a standard request because memory is less expensive then adding it later. The 160 user is a bigger thought. You call it an app server. Is it RDS or holding the code to be served up to the requesting workstations. I this is the case then throughput is more important. 160 users accessing the code off an app server via a single network connection will cause backup. The reseller is doing you a favor by making sure you buy more server then it appears you need. If you are on a HV cluster you can move the resourses around. If this is a stand along HV server and you have both SQL and App server you may be overloading a single machine.