And the gist of that link is:
"Recent Understanding Seems to Be:
Add Nothing to Rom, except what is Absolutely Necessary.
(Although Opinions Vary)"
It must depend on what each of us want to get out of our Treo, but for me DB Cache is king, so I'm striping bits out, and adding nothing back except FAT32

I guess for the most part I agree with putting as little back in as possible, but there does have to be some balancing point where the effectiveness and efficiency of clearing ROM space is maximized.
I think it's sorta like the "chicken and the egg" discussions. From what I've read on TC there seems to be some differences of opinions.
i.e. One user says it's best and his Treo screams with a custom ROM (with and original partition of 8.4) and his stripping and reducing the partition size to 7.1. OK so he stripped out 1.4+MB of ROM and then reduced his partion size by 1.3MB. Where's the gain? Other than more Free RAM.
Then another user strips the an 8.4MB partition to 5.4MB, and puts 1MB back in, his gain is still more than 2MB Wasted (Free ROM), still a bigger gain than the other fellow who used the gain to reduce partition size and Free mor RAM.
Whose is more efficient??? To quote
mmastrac, right here in this thread:
The general guideline is to make your ROM partition as small as possible to increase your available NVFS space and to store as little as possible in ROM to increase your available DBCache (aka storage heap).
When you are talking about applications totalling less than 500kB (rough number), you can probably skip some of these guidelines for the convenience of having applications always around. It's basically all about balancing DBCache/free NVFS/etc.
and then...
The
biggest advantage to custom romming is that you can delete the carrier-specific crap from your phone and reclaim memory by deleting unused applications.

This tool is designed to use your current ROM as a starting point. From there, you can delete stuff (like the carrier files I mention above) and replace stuff (like FATFS->FAT32).
I started with:
Software: Treo650-117-CNG
Firmware: 1.51
Partition Size: 7.1MB

The I started experimenting and I've ended up with a much faster, more efficient Treo, with a MAJOR improvement in audio quality and clarity. I didn't even have to put VolumeCare back on because the clarity and volume is better now than it was with the Cingular Software and VolumeCare. Evening with increasing the ROM Partition size and changing to a FAT32, after installing all of my app back to the Treo (minus the ones I added to ROM) I still have more free space in ROM and RAM than before.
I think as mmastrac said,
It's basically all about balancing DBCache/free NVFS/etc.and ended with
Software: Treo650-171-120-ENA
Firmware: 1.20
Partition Size: 8.4MB

**ROM Size, RAM Size, and Free RAM were determined by FileZ
**Largest ROM Size, Current ROM Size, and Wasted Space were determined by RomTool
**DBCache Size, DBCache Free, and DBCache Max were determined by DBCacheTool
**Speed was determined using Palm Internals