Lion, Leopard, iMac and Audio Software...

The benefit is that there is no guarantee that all the software you want to use will work flawlessly with Lion on day one.

The best strategy would be to get the iMac now (or soonish) and wait for Lion to get updated to 10.7.2 or so before upgrading.

If by "kernel-screwing-around-with," you mean that those software suites heavily rely on or even modify system resources of the operating system they run on, then that might be grounds to believe that it might take a while for these to be patched for Lion compatibility. Perhaps as a general reference, find out how long it took that software to get patched after Snow Leopard was available in retail stores. It's possible the developers are toying with pre-release builds of Lion as we speak and will have updates available on day 1.

There's a similar thread in these forums with your basic concern. My advice is the same: If you want an iMac now, go for it.

If worst came to worst, you can always withhold from updating to Lion until the audio software you rely on is compatible. Otherwise, you may be waiting a while: The time for Lion to release (2-3 months) + The time to issue a software patch (only the developers know how long this will take.) And if you want to, you can always dual boot Snow Leopard with Lion and switch between them, based on what sort of work you have to do - Snow Leopard for audio work, Lion for everything else. It's pretty simple.