Hi Flalar
Short answer: No, performance-wise 10 concurrent connections are too little. I'd definitely set it to 100+.
F5 is already aware of this and there's an RFE tracked by ID 848545 internally that suggests such changes to comply with RFC's recommendation but at the moment there's no target version so I believe we should still see the default of 10 for a while.
I believe we should eventually move the default settings to 100 and that makes the most of HTTP/2 parallelism. I don't see any downside from increasing number of concurrent connections. However, In the event of an attack, for example, in scenarios such as H2/H1 (HTTP/2 Gateway), an attacker could potentially be able to exhaust BIG-IP resources faster.