Cyrus said:
I think the main lesson is, don't have them vertical: but can't them inward or outward depending on what the aerodynamics favors (for a similarly obtainably RCS in either configuration).
Edit: While I don't necessarily doubt the claim by Boeing that the angle decreases RCS, I also don't put it past them to lie and say this to boost sales of the aircraft. Without actual comparison of RCS of the E and SE models to actually show if the tail works - be skeptical.
It's not that they're vertical, but that they're not at 90 deg angles to the wings. That said, canting inward is better for deflection against ground-based radars, but worse for low-level operation against lookdown radars.
The SR-71 did not employ radar absorbant material, so canting was their only option given the high heat-resistant requirements, and given their high-altitude profile, canting inward was the better stealth choice, even if it resulted in slightly degraded slow flight performance (drivers said "it wallowed").
The F-15SE's operating environment is less heat-restrictive, allowing the use of far better radar-absorbing materials (though some are simply translucent or transparent to radar).
I agree Boeing is in the market, but given their engineering expertise, they have little need of stretching the truth. I think they're main goal is to sell it as a much lower-cost but nearly capable alternative to the far more expensive F-22 and F35.
Besides - we have lots of potential targets around the world that don't require "the best of the best of the best" in technology. Just look at how admirably Sandy's (A-1 variants) and similar aircraft performed in Vietnam. It was a 40's-era plane that kicked butt twenty years later!
Interestingly enough, the plethora of variants created somewhat of a maintenance nightmare. Fortunately, most of the versions involved ancillary equipment to the basic airframe and powerplant. Still, it was a lesson in how not to modify an aircraft into every conceivable role.