i’ve been doing that with some mates too. lovely thing, ain’t nothing better than a straight livejam. and yeah, having to beat-sync once every few minutes plainly sucks…
do you have a soundcard with midi-out on one of your laptops?
if so what you need is a simple usb-midi device (e.g. one midi in, one midi out, connected via usb) for your second 'puter. wire the midi out of laptop 1 to the midi in of laptop 2, set laptop 1 master and laptop 2 slave (in the midi-options), Bingo!
btw if you don’t have a soundcard with midi out get yourself two of these usb-midi things, they are not that expensive (about 50€). maybe there’s a cheaper way to do it but this is what should work.
I actually got this going late last night, using emulated MIDI through my LAN connection I am using a program called MIDIoverLAN.
It works great, but I noticed last night (this happened twice) that after several minutes of syncing, the slave Renoise would skip BPM and adjust to double the BPM… still syncing, but not with the desired effect, heh…
In other words, master Renoise set at 128bpm, sync begins with slave Renoise at 128bpm… then after several minutes, all of the sudden slave Renoise jumps to 256bpm.