Most Mercedes brake calipers have chromed bores that cannot be honed. Rebuilding the caliper only involves replacing the seals and dust boots. You really need to inspect the bore in order to make your decision. If the bore and pistons are in good shape, the kit would likely be the way to go. I would also replace the pads, flexible hoses and rotors. All reasonable DIY jobs. And repack the wheel bearings while you are at it. (Amazing how one thing leads to another.)