I've been using the 9030 with different setups - within the effects loop of a preamp in a rack system, and as a preamp/processor into the input of a combo, using the 9030's own distortions. I's essential that you turn off the horrible speaker simulator when not recording directly to tape - or even then - and make the necessary utility settings - otherwise the unit sounds laughably thin and muddy - like most of the presets, of which most utilize the speaker simulator. Compared to current units the 9030's effects generally sound a bit too "digitized" and thinnish to my ears - especially the flangers and phasers, of which the latter does not sound like a proper phaser at all. The SFX are funny, but not very useful, and the intelligent pitch shifter isn't very intelligent... The delays are really good though, epecially the complex stereo "echo", although the tap tempo options are ancient. The tremolo is another highlight, with a very useful parameter selection. The distortions does in fact sound OK through a good amp, although the "crunch" is horrible (use lower gain settings with "OD" instead). The choruses are also OK, but you have to make some silly compromises as far as effects combinations are concerned; if you want, for instance, chorus and delay, you can't use the stereo chorus, which resides in the same effects module as the delay, but you have to use the far less disirable sounding mono chorus, which has only two chorus parameters (effect level and depht - the rate is fixed!). When connected in the effects loop of a preamp you'll notice that the unit steals quite a bit of the preamp sound, making it harsher and muddier. It's not critical though, but annoying, as most current units will not do this. The noise level is quite low; if you listen very carefully, it sounds as if there is some internal noise gate in the unit, as a signal's last second of decaying sustain will be cut off. When changing patches the 9030 mutes the sound far too long for my liking (about half a second), and the option of turning effects on and off is not very useful, as the the unit also in this case will mute the sound, as if you were changing patches.
My 9030 has never let me down on a rehearsal or a gig (the 8050 foot controller has though), and after five years of use the lithium battery still works. The EQ module lamp goes out occasionally, but it's not a very big problem. When using it live with my current setup, my only fear is that the memory goes down due to the lithium battery (as I don't mind changing it). Thus I run it in the effects loop of my main processor, so that I can bypass the unit if it goes down. I only use the 9030 for particular effects these days, for instance only as an additiolal tremolo unit.
The 9030 was a good and useful unit five years ago, but is now superseded by today's far better units, which have less limitations concerning the effects combinations, steal a lesser amount of your preamp sound, and have faster patch changes. Today's units are in general far more well-spec'd, and you get more for your money now than then. As mentioned above I'm kepping the unit just in case I need to throw in an extra effect to make some REALLY complex sounds that rquires more effects than my Roland GP-100 has on offer. I've not come to that point yet though... Anyway I can't part with my 9030, and it certainly still looks VERY nice in the rack...