"Remember when computing was fun" lol just kidding...
It is important to remember to not dig a hole to deep if you are going to enroll yourself in this hobby.
On paper a maxed out A4000T with PPC and occupied Zorro slots incl PCI sounds like a great idea, most often that is not what a typical next millennia Amiga user needs. It will take a lot of space, use a lot of energy (110watt + ), and in some ways do the stuff you want to do with it worse than a basic A1200 with turbo/fast-mem.
I am happy with my A1200 060, suits me like a glove for what I need it for.
http://www.youtube.com/watch?v=6P7aqoQGVhsI got PCMCIA/CF-converter with FAT filesystem, can transfer files easy to the Amiga, no need for messy network. Indivision with HighGFX, no need for RTG boards and big box system, do you really want to spend a week perfectioning a PNG WB anyways?! is that fun? WB3.1 so you get total control of your setup and old school icons that looks good in either hires or hires laced. And most important, I get 100% perfect sound without screwing with WinUAE.
And finally the best thing with it, once I am tired of it, I can put it in a box in my closet until the next time I am ready to remember have fun again with a computer.