Ultimately we've done everything we can to ensure you don't get notifications. We use the delegation access mechanism that Google Recommends (OAuth) and if Google continues to give messages or warnings there is nothing we can do about this, and the fault for this does not lie with us.
Also remember that Google don't necessarily want you to use your GMail as a storage account. This is why they Provide Google Docs and Google Storage (and we support both). We are able to let you use GMail as a storage account by some clever coding and access, and it's you choice whether you use it. The drawback are perhaps the message you see, but I have to say we don't see the message you see using the OAuth mechanism.
When we use Gmail as a storage cloud (via delegation access) then we can see that the Account was accessed from our IP if we login to GMail and look at the last activity at the foot of the page:
and if we click the link we see the full details:
You will notice also that Google (correctly) lists the IP address from the USA here.
You also state that Gladinet does not have these issues. Well, I see that Gladinet does not support using Gmail as a Cloud storage provider so I doubt they would.
As stated earlier we have done everything can to prevent the warnings and the decision whether to use GMail as a storage cloud is of course your own. We provide access to plenty of other storage providers that you can use if this is to much of an inconvenience for you.