Alex, look into the HDS systems lights, and you may find there can be far more hype and fanboyism than actual substance to those lights, and we will go into detail on that. But for recommending a light, the question is, does it have to be a rotary light? If not, I would recommend Zebralight for the following reasons.
(a.) All electronics are fully potted just like the HDS for ruggedness, and the lights have a strong reputation of robustness and reliability. More so than any other Chinese maker.
(b.) The 18650 model is SMALLER and LIGHTER than an HDS 16340 model, all while offering nearly 7 times the battery capacity in a smaller and lighter package.
(c.) Can not only output over 7 times as much light as the brightest HDS, but also has the option of running a reduced output equal or better to the HDS, and still provide just as good, if not better runtimes, along with no overheating due to the excellent design. All while having access to 1000's of lumens at an instant if you need it, and not being stuck with the paltry 325 lumen output of the HDS.
(d.) Zebralight is much more efficient at lower brightness levels. The HDS is actually inefficient at it's lower output settings. This is documented.
(e.) Most Zebralight models have more throw than comparable HDS models. The HDS has a throwy punchy hotspot, but Zebralight can win on sheer grunt. They also make an SC600W HI model that would be a good comparison to HDS on throw.
(f.) Machining, threads, and anodizing are phenomenal and of the highest quality available. Hold one in hand, and you will be convinced. I've held the best, and I am convinced. Hold the HDS and Zebralight as the same time, and tell us if you see anything to justify triple the price.
(g.) The UI and what is best a subject thing, but I, along with many, many others feel the Zebralight UI is the best on the market. Not only does it allow you to fully customize each and every output level (six in total), but it allows you to instantly choose between Low, Medium, and High all instantly. You also have three different mode groups you can configure and save. The HDS does not have this capability.
(h.) No compromised drill hole in the tailcap. Yes, the HDS design actually contains a literal drill hole in the tailcap, which they used to actually send out just bare until customers started complaining. Now, they fill the hole with a small plug. Some will argue that this hole isn't a compromise, that it's above the Orings. This is false. The drill hole is completely a compromised design, and an exceptionally poor one at that. The water/material that could potentially enter the light and be stopped by the oring would never had entered in the first place had the hole not been there. Furthermore, I recall a report of someone getting sand inside the hole, and having to have the light disassembled to remove it.
https://www.candlepowerforums.com/v...HDS-Rotary-Why-is-there-a-hole-in-the-tailcap
(i.) Quality control. At HDS, emitters that are lazily and sloppy off center, cracks in reflectors, ringy beams, LED's that aren't even properly soldered to the pad, poor quality knurling jobs, and cerekote that the fingernail peels right off are considered "Cosmetic" issues and are not covered by warranty. In fact, the QA is poor enough that they have actually made a page on their site dedicated to addressing this, and proclaim that these poor workmanship practices have no bearing on the lights actually performance or utility. Basically, charge for perfection, but provide less than that. Google these issues here on CPF, you may be surprised.
https://www.hdssystems.com/Content/LightFaq/
(j.) Not sure where you are located, but to us American's, being made in the USA is an important thing. And Zebralight, although manufactured in China, is a US based company, and the lights are designed right here in the US by Americans.
(k.) Costs 1/3rd of what HDS wants for what can be argued is a lesser light. $89 to $99 dollars versus over $300 for the base model Rotary. If one wanted an 18650 HDS, which is double the size and weight of a Zebralight, jack that price up to over $400. Ouch.
Hype and fanboyism is a very powerful thing. One not need to look any further than the first page of this thread for it. You indicate that you want an HDS, but are leery of the price, and a suggestion comes in to go all in and buy a special run edition of the same exact light, but in an exotic metal/finish, for double the price of what you have already indicated is too much money. :shakehead
Some of the responses you can expect to see is "But the HDS can be smashed off the wall over and over, be shot by shotguns, and still survive". Yeah, so can other lights too. Check into how many failures of HDS's you can find reports of, you may be surprised. It's far from the totally indestructible light the hype would lead you to believe.
And finally, don't get hung up on the "Made in the USA" part too much. What you will find is many of these USA made premium lights are filled with overseas parts that are no different than what other makers are using, instead you pay a premium for the name branding.
If you don't NEED that rotary, then I suggest you really give Zebralight a look. They are similar to HDS in that, they have been perfecting their design of the same light for years now, each and every new model being generally the same as last, but with refined improvements. Basically, the same as HDS claims, only with real performance and data to back up the said improvements.
EDIT: Also noticed you asked for a tailcap switch. The Zebralight has the traditional type switch position, but it is very good, well placed, recessed yet easy to find, and feels very natural and easy to use.