In many cases, the profile drag increase from dropping the Reynolds number can outweight the induced drag benefits of a higher aspect ratio. This is part of what influenced the results on gliders quoted before.

For instance, if we start at Re=200000, and double the aspect ratio, we will recuce chord, and therefore Re, by a factor of 2.

For a sample airfoil, this increases profile drag (Cd0) from 0.01 to 0.014, which will significantly reduce top speed, as well as attenuating the turning benefits of the higher AR.

It's a very complex and mission-dependent problem, and increasing AR may very well help you, but I just wanted to point out the physics behind some of the drawbacks to high-AR wings on models.

Above about Re=300000, these evvects become almost negligible. Below Re=100000, they are incredibly important.