I've got Boras and have been experimenting extensively over the last several years with different tires and widths trying to ascertain how much of the marketing spin is real and how much is hype.
I'll limit this to tire choice on your 2014 Boras. I've used Conti Comps 22mm, Veloflex Carbon 22mm, Veloflex Carbon 23mm, Veloflex Roubaix 24mm, and Veloflex Roubaix/Arrenberg 25mm tires on these rims.
I personally avoid Conti tubulars now, not because I think they are bad tires, but simply because they are so much more difficult to mount on the rims, even with proper stretching. But that's the only reason, I like their tread (dots) and tire compound. I suppose they're stiffer but you can compensate for that with lower pressures. Nuff said on that. And their thick cotton base tape sucks up glue like a sponge.
For tubulars I stick with Veloflex exclusively now. For clinchers I like Conti 4000s II.
Here's the deal with 23 vs 25 Veloflex on Boras (pre 2015). They're both great. You run higher pressures with a 23mm than you will a 25mm and the 23mm tire will feel noticeable firmer on the road. The 25s are much more comfortable for sure.
Stability: One thing I found with high tension wheels like the Boras is that (at 200lbs/90kg), with 23mm tires they could tend to feel a little sketchy sometimes at speed, almost like I was going to go into a speed wobble maybe when you hit some sudden imperfections in the road. I don't like that feeling. I should point out the "stability" I'm talking about here is to be distinguished from wind effects and getting pushed around due to a higher profile rim and crosswinds. That's a completely separate thing. So, that's the main reason I wanted to experiment with 25mm tires. I put them on and sure enough, most if not all of that feeling went away. Perhaps it was the damping effect of having more air volume between the rim and the road and the ability to "move" a bit more fluidly, but whatever it is, I tested them long enough to know that it's real. So, a 25mm tire on a pre 2015 Bora is going to be much more comfy than a 23mm and (at least if you're a bigger guy) it will add to how stable it is as well, significantly.
Speed: Here is where I'm not at all convinced that a 25mm tire is simply faster than a 23mm; it's not as simple as that. There's all kinds of crr tests out there that will state there is less rolling resistance etc. But in my experience a 23mm Veloflex tubular, say at 105-115psi, seems to be a faster rolling tire (albeit firmer), than a 25mm version of the same tire on the same rim run at say, 90-100psi, which are a good representation of where I usually am with these tires. You can adjust the ranges for your weight accordingly.
Rim profile: I had no issues with gluing up any of the tires I mentioned onto the Boras. The Bora rims have a nice smooth profile and seem ideal for 23-24mm tires, and I had no problems with the 25's either. I don't see that I would ever want to run greater than a 25mm tire on my road bikes. The only issue I had, which was more of a nuisance than an issue, is that with the 25mm tires mounted and the brake calipers adjusted to the rim where I like them, that upon removing the wheel it was a bit more of an effort than just simply opening the quick release and having the wheel come out. The added width of the tire would get squeezed in the brake pads (even with the brakes "released") and I'd have to give a healthy nudge to pop the wheel out with an inflated tire.
So there you have my 2cents. The next thing I want to test is to mount a 23mm Veloflex Carbon on a 2015 Bora 50 to see if the wheel is more stable than the 2014 Bora with the same tire. I suspect it will be but I hope to be able to separate just how much of that stability increase is due to say, a wider tire, and how much the wider rim. I have a feeling that simply putting on a wider tire may have more of an effect than simply widening the rim but not the tire. I'm looking forward to testing this out.
The new 2015 Boras are very very nice I must say. I'm especially pleased with the chosen 24.2mm width on both front and rear. It looks just right to my eye and for the tires I run. Uber wide rims (like in the 27mm range for road) sometimes get into brake pad clearance issues, etc., or it becomes a real pain in the ass switching wheels around.
So, in the end the choice is yours, the rim profile will work just fine with either the 22 (continental) or 23 (Veloflex) or 25 (Conti/Veloflex) just fine. The "aero" advantage you speak of I suspect is indeed very marginal at best. But the handling characteristics are quite different between the two. Still, if it's all out speed you're after, I think the 23's would be your best bet. Experiment with both over time, that's the best way to get it right for you.