Meanwhile X11 is more profitable at the moment.
Side calculus, I assume that for your farm of (if I understood correctly) mainly 280x you have a ~6x scrypt factor for x11 and a ~4x scrypt for x13 like I have with my 290s. Basically, since WP marks them as 4x and 3.5x, the vsLTC has to be at least 30% higher for x13 over x11 to be worth mining.
Coupling this with the fact that the reported BTC/MHd or the vsLTC figure are at least 12 hours old it becomes difficult to anticipate the moment we need to switch algo. For example, now it feels like the X13 is more profitable since the profit is rising while on X11 it's falling and since what we mine now gets converted at a later time I think basing our switch on trends and not fixed actual numbers might be better.