If you are truly learning how to be an audio engineer from scratch, I don't think the Digi003 is a bad investment at all. (I have a Digi 002 Rack and an Mbox, so no Control surface advice.) The preamp and converters are going to be usable for you for awhile unless you are a particularly gifted and fast learner.
I am nowhere in the league of the gentlemen offering you advice, but I can offer you my experience. I am a semi-pro weekend warrior musician and a songwriter, not an engineer, so bear that in mind.
I have been making multitrack home recordings since at least the late 70s with 4 track reel to reel decks and Portastudio cassettes. I have been in the digital recording world since about 2001 and after throwing a pretty significant amount of money at this, here is what I have found.
*The person doing the engineering is really about 99% of the game.
*You have to have a great song and great musicians to record or the whole exercise is pretty pointless.
*You will make a much more profound difference in your level of skill by learning mic placement and how to listen than you will in spending lots of money on pro gear.
*Apprentice at a local studio for free as time permits if you are really dedicated to this. Don't expect to be paid. Empty the trash, make coffee, whatever they ask. Keep quiet and watch and listen.
*Hearing the difference in preamps and convertors is apparently something that pro engineers and maybe animals can hear, but not me. And I think that as a regularly working musician, I have pretty critical, albeit partially lost, hearing.
*You asked about Harvey's forum. I think it may serve your needs better since you seem to be new to all of this.
*Print the document out at this link and read it constantly.
http://www.itrstudio.com/MIC_CHAT.PDF The knowledge in that thread is worth way more than a $2,000 preamp.
I am not seeing anywhere whether this is just going to be a hobby for you or if you are recording yourself as a singer or songwriter or musician or whether you intend to do this as a business.
If this is just a hobby or you are a part-time musician like me, I say keep it simple and get something along the lines of the Digi 003 or even just an Mbox or the equivalent for learning the basics. None of the pros here are going to be using or recommending those preamps for making commercial release recordings, but for learning purposes and some really high quality demos, they are more than good enough.
In all my searching the web for samples of the differences the gear makes, I have concluded a couple of things:
*Based on many recordings I have heard from home recordists (not in this forum) who have spent a LOT of money on gear, those recordings still do not sound professional to me. There is always a little something missing. Usually it is the song or the voice because they are trying to do it all. But the recordings do not sound like records to me, just really good demos at best.
*Recordings I heard done on a prosumer 1/2" 8 track Tascam by a pro audio engineer here in Austin back in the 80s have a more professional sound than many recordings I have heard done by home recordists with a lot of high end gear. The difference is he did and still does recording for a living.
*It has taken me decades to know everything I know about writing a song and playing bass; I am far from the best, but I have grown because I love playing bass and I am obsessed with songwriting. I have been recording for decades, but I have not progressed that much because engineering is not my passion. I spent somewhere around $5,000 to figure that out........ If I had it to do over knowing what I know now, I would have just bought 2 decent mics and an Mbox for demos and if and when I wanted to record a CD, I would take those tracks to a real studio with a real engineer and let them do what they do best.
Is recording your passion?
One last thought, not sure what kind of truck you drive, but - if I went out and bought the most expensive rig that money can buy..... would it make me a trucker? What makes you a trucker, the years of time you put into it or the brand and quality of the rig you are driving?
bilco