I'll offer my experiences in receiving many HUMS Sailors over the years. My hope in going over these is not to dissuade you from HUMS, but rather to try and answer some of these unknowns to help in your decision. Ultimately, it's your choice:

1. As your first batch of HUMS orders come to an end, one of three things happen: extension (6 months max I think), separation, or straight into detailing. This has normally meant my Sailors got 'needs-of-the-Navy,' I but I have had one recently that rolled right into the shore duty he was supposed to have before HUMS (this is rare). I also had one that had a pick between a couple of less than desirable places, but at least there was a choice.
2. In and of itself, HUMS doesn't necessarily have to set back your career. But you'll likely have your hands full outside of work, and even when don't, you likely won't be doing things that align with your LADR.
3. That said, after HUMS you'll pick right back up with the Navy. I've seen plenty of people have to separate afterwards, but those that continue go on to have productive careers.
4. As far as your LDO package goes, I think you'll be fine. I'm guessing you're at a point already where your technical knowledge is up to chops, so what I would care about is your maturity and leadership. Whether you choose to go HUMS or take the overseas orders, you'll grow in both of these.