Handheld GPS: Garmin Colorado and Vista HCx

My Garmin eTrex Vista HCx, which I've had for less than a year, may be lost forever, so I'm looking for a replacement.

The obvious first choice would be the same thing, an eTrex Vista HCx.

However the new Garmin Colorado, either 300 or 400t, are worth considering.

Some considerations:
--size: Colorado is 2.4"W x 5.5"H x 1.4"D, HCx is 2.2" x 4.2" x 1.2" (the Garmin web site, for some reason isn't consistent in listing W-H-D in the same order)
--weight: Colorado 7.3oz; HCx 5.5oz
--display size: Colorado 240x400 pixels - 3" diagonal; HCx 176x220
--battery life: Colorado 15 hours; HCx 25
--chipset: Colorado- Garmin proprietary; HCx SiRF III
--datacard: Colorado SD, though it appears that 4GB is the limit supported with SDHC; HCx microSD

Some unanswered questions:
--the Colorado has a "Transflective color TFT"; the HCx has 256 level color TFT. What's the functional difference, if any? There is at least one report that the transflective TFT technology is less readable out of doors as well as discussion about the display.
--apparently the Colorado lacks a "night mode," which affects the screen brightness and colors displayed.
--is startup time too long?
--is Trackback feature needed?
--USB 1.1 only?
--no street names with City Nav loaded
--no waypoint averaging
--map borders clutter screen (I've seen this on other units)
--lists don't scroll around, but have a beginning and end
--zooms only to 80 feet

This page lists many perceived deficiencies and this one lists issues.. It's hard to know which of these can be changed/fixed with a firmware update, assuming that Garmin wanted to make the change in the first place.

One concern I haven't yet seen mentioned elsewhere is, with the non-SiRF chipset, can the Coolorado ever take advantage of Ephemeris APGS to reduce time to fix. Perhaps the function or its equivalent is already included?