[LAU] Fluidsynth versus Qsynth, .sf2 versus .gig

I keep on getting Xruns when trying to work with soundfonts on rosegarden or muse, especially if I combine several sf2 banks with several audio tracks (on Ardour, prior to use plugins). So far, I was running them through Qsynth, but I read on the net that the combination of Qsynth, Rosegarden/Muse and Ardour is regarded as not so stable? Thus, if you don't mind sharing your experience, I will be thankful. What is the best way that you use Soundfont banks in Linux? By 'best', I mean the most stable way, without X-runs and listing/access to all the banks and instruments in a soundfont. Is running fluidsynth from a command line a better alternative then qsynth and why? (fluidsynth command line: how does one create a midi input and audio output port for each sf2 bank?) Can you please tell me your experience in buying professional .gig or .sf2 sounds? Strings, pianos, accordeons especially. Sites, prices, quality? What is better for profesional results: .sf2 or .gig? thanks in advance Viktor