I often VPN to each location and if I can I would like to start encrypting the data between each sever.

I was using a pair of bufflo's with DDWRT then I upgraded to a couple of PFsense boxes but need to swap them out (heat/power/space)

cisco ASA5505 with a Geode 500 and 512mb (Security Block instructions) (8xGBE)
pfsense box with a Via C3 1GHZ (padlock instructions) (4 10/100)

not sure whats faster or if i should keep the ASA at my location for its added features?

Im kinda liking the new PFsense box, and keeping them both the same would be nice.

any other reasons to go with one or the other?

i would think the PFsense box might be faster but the ASA has alot more ports….