We have a number of ESXi hosts on separate management VLANs with different default gateways. We always managed with one host profile because we could disable IP routing from being applied which ensured the default gateway is left alone when applying the profile.
Since upgrading to v5.1 our master host profile no longer worked, so we were forced into re-creating it. This we could live with, however we have also found that when we apply the host profile the default gateway is always being removed, even though we have it set not to apply any network configuration. The result is our hosts now drop off the network when the host profile is applied.
One of the symptoms is documented in KB2040943 and is described as a 'cosmetic issue', yet it seems to be more of a disturbance for us.