As some astute poster pointed out, this is a business decision. By going with an agency, IMO, you hand over to them a couple of important business elements:
1. Marketing. You have carefully constructed and burnished a "brand", in your case that of an independent, intellectual, outside-of-the-ordinary companion. An agency has its own brand, which is unlikely to mesh seamlessly with your individual sensibilities. They will not be motivated at all to protect your painstakingly constructed brand credibility. And once it's gone, (Toyota, Tiger) it is really hard to restore it. And, sorry, in this day and age, there are no regional boundaries to something like that, no "secrets". Most especially if you hope to try this out with your existing nom-de-budoir. Oh, and there's no "part-time" when it comes to brand.
2. Security. Regardless of their record or protestations to the contrary, no agency will take your safety and security as seriously as you do yourself. You relinquish the "this just doesn't feel right to me for some reason I can't put my finger on" control. You'd be playing viola with gloves on.
But the question you asked is whether it would matter to a LTR if you took this route. Regardless of what we like to think, LTR's are as susceptible to number one above as anybody else. He or she might say they couldn't care less, but stupid as it sounds, a little of the "specialness" of your brand is likely to slip, making him or her vulnerable to the competition's blandishments. Which are legion and relentless, as you know. If you're serious about keeping those LTR's for the really LT, I'd think really, really carefully before taking this route. Which is why you posted, of course.
I imagine you're asking the question because it's tedious, annoying, frustrating and time-consuming to do the marketing, screening, and general establishment of your brand in a new market. (I can't help noticing that your Web site isn't maintained as persistently as it might be
. Marketing's a PITA, especially when you're doing it yourself, and trying to keep up with business and life at the same time.) Welcome to the business world. An agency can take that off your hands for a fee, but you relinquish at least part of the controls mentioned above, and possibly others.
It's a business decision, but in my experience, a business decsion should never be made because business is hard (pun NOT intended!) If you plan to continue in this lifestyle for years to come, I'd counsel you to very carefully consider the damage to your long-term brand credibility. If you want to establish yourself in other markets so that you can travel and explore long term, on YOUR terms, I don't think there's any substitute for the painstaking establishment of your brand, as you want it to be established, in that market.
Look at the best of the best in the marketing area (Lauren Summerhill, others), and ask yourself if this is something she would consider.
God, I can go on, can't I? Sorry about that. You got me thinking.