I don't really regret selling off my totally expanded A2000. I had so much stuff in there - an 040 card, 32MB RAM, a 16 bit audio card, a MEGA-chip, a flash-ROM card, a SUPRA-RAM expander, CD burner....and more that I don't remember. It was a beast of an A2000. I heavily used and loved this machine, but with all the expansions there were conflicts between hardware. It required a lot of patches to activate the hardware, and these had to be carefully arranged in startup-sequence to avoid conflicts. It was kind of a giant (but fun) kludge. Sometimes it took a few reboots to get everything to start up and be recognized.
Eventually, I think, there was just too much loading the power supply and it became slightly unreliable. It was also very noisy with all the fans, etc. It sounded a bit like jet plane starting its engines.
After I sold most of it off, I started using UAE and was totally SHOCKED by how good it was. I could do all I had done with my expanded A2000 and more and it was SO FAST and compatible. It even looked exactly like a real Amiga on the monitor (especially when I was still using a CRT monitor with my PC).
Since I don't do a lot of gaming, but was a heavy productivity software user (graphics, music composing, etc), all the rendering and heavy CPU functions were now blazingly fast, bootup was quick, drive access was like lighting and I had access to almost unlimited RAM. So I actually became way more productive with Amiga software after I switched to UAE.
I did keep the original A2000 (computer only), and set it up as a "bare bones" 68000CPU Amiga. I also keep a slightly pimped out A500 (only expanded with 8MB RAM, a hard drive, Mega-chip and HD floppy). These are in storage for when I get the desire (and space) to use real Amiga hardware.
One of the things I love about using these "bare bones" (almost factory default) 68000 Amigas is that I'm back to basics. Using the hardware that Commodore provided from the factory. Working with Paula, Agnes, etc. instead of bypassing all of the original hardware with RTG graphics cards and audio cards. My A2000, with all its expansions, was almost not an Amiga anymore. So much of its functions relied on third party hardware addons (audio, RTG, CPU, etc). When I use the "bare bones" Amigas, I'm back to using DPAINT in native HAM mode, or working with the native 16 colours, or tracking music on the native 8-bit PAULA audio, etc. It's more fun because it's retro. It's seeing what can be done with the original factory default hardware, rather than bypassing it all with third-party peripherals.
And, when I need to do serious, heavy production work on the Amiga (like Lightwave rendering, or ImageFX, etc) I'll use UAE.
Plus I think I predicted things well. I sold off all my A2000 peripherals when they were selling for a nice price. I reasoned that in a few years I would probably be able to replace them all with an all-in-one, cheaper, more reliable, modern device that would do all that they did and fit in a single Zorro slot. Since then, the VAMPIRE and other FPGA devices are coming along nicely, so I think I might have made the right choice for if and when I want to pull my A2000 out of storage and pimp it out like it was.