Our rails are designed to work with standard mil-spec uppers. Typically the tabs need to be removed with billet uppers (or non-mil spec uppers) because they are too wide for the handguard (this is the modification we mention in the product page).
However, it is possible to save most of the tabs with some billet uppers. You still have to grind off part of the tab, however, if you remove some of the inside (instead of just taking them off all together) it will work. Basically, you just need to slowly remove the inside of the tabs until they fit around the width of the upper. Depending on your upper, this allows you to keep the tabs and allow the handguard to fit. If the upper is still too wide after taking off part of the inside of the tab, then you will have to go ahead and remove the entire tab.
Due to the way we designed the handguard, and the built-in redundancies in place, you won't lose functionality if you pursue this modification. Customers frequently make this modification without any issues to date. The anti-slide plate feature is still active which prevents sliding of the rail. You can also add blue loctite to the barrel nut which gives the same result as having the tabs, although it is not a necessity.