thojo - I just looked at one of the modern combat models. The high aspect ratio isn't ideal for good roll response, something along the lines of a modern IMAA airplane is better being a compromise in roll acceleration and damping.

The high aspect ratio airplane would seem to double your chances of getting a ribbon cut (compared to a "normal" configuration) - then since with models we usually have more than enough roll rate the penalties in roll due to the high aspect ratio (high Clp and roll moments of inertia) are easily handled. The modern combat model did have a short tail moment arm and small wing chord which gives lower pitch moments of inertia and good pitch response.

But the configuration is driven by things other than optimum maneuverability - cutting the ribbon being the main one.