Can The ASM be used with a fast-L4 Profile. Would all protection features be available?

I don't believe you can use ASM with either fasthttp or fastl4. When you select the vs type other than standard, i.e. performance (http) or forwarding IP you do not get the option to add either a http class profile (pre 11.4) or a local traffic policy (11.4 and above) in order to route traffic via the ASM module.

N

There are some trade-offs here. In ASM v13.1, you can apply Performance Acceleration in the DoS profile. A Performance (FastL4) virtual server has a FastL4 profile assigned, which increases the speed at which the virtual server processes packets. This virtual server can take advantage of Packet Velocity ASIC (PVA) hardware acceleration present on the BIG-IP system, but at the expense of inspecting any layer 7 application data, such as HTTP payload.

By selecting Performance Acceleration in the DoS profile, you ensure most of TCP flows will be forwarded to the application without HTTP inspection. This feature must be used with care. If performance is more important than security processing, then note that Proactive Bot Defense, Bot Signatures, Device ID, Client-Side Identification, and CAPTCHA (all of which operate in full proxy mode) cannot be used. However, if ASM detects an attack based on behavioral analysis or server health check, all suspicious flows will be fully proxied, inspected, and mitigated.

The trade-off (for now) is that Performance Acceleration cannot be applied to a virtual server with an application security policy because we still need to inspect the HTTP payload.