ORIGINAL: -StephenSampson-
h5995 is same price as 5955 (both are titanium gears) and the 5995 has 333/416 oz/in of tourque and .15/.12 speed. only thing is it wont run on 4.8v. it needs either a 5 cell or 6 cell pack but really most people have at least 5 anyway (or you could just use a 2 cell lipo and it would be even lighter. you would need to but a power expander to do this but it would be awesome.
plus power expanders are better for your receiver than just plugging the battery right into it and then feeding the power out of it to each servo. with a power expander the receiver is only used for the white wire (the signal)
Although some *have* used them, I don't think Hitec recommends the 5995 (which is a robot servo) be used on model aircraft.
For a start, you'll need the Hitec programmer to cut the throw back from the standard (for a 5995) 90 degrees each way to 60 degrees each way.
There are no benefits to the 5995 over the 5955 for model airplane use and some disadvantages.