I agree that loose option can be good, but only if you have a plain network without some security zones, what I mean is that if you have firewalls between you point A and B the firewall will be stateful and because of that it will block the traffic before the F5 so the loose option will not be in use.
IMHO a firewall should do firewalling, a router should do routing and a ADC should do loadbalancing as far as you can.
Some service I know by myself can´t be used with SNAT so then the F5 will be the router.
SNAT is also not so fun for server administration guys but they can be learned =)
Good though that this topic came up =)
Regards,
Beinhard