Robostix vs Technologics ARM SBC

An interesting comparison of Robostix/gumstix and the technologics ARM-based SBC is here.

I don't think I would need the robostix component, just a connex (Intel XScale® PXA255 400MHz). The Vex is going to be doing the sensing, after all.

To interface to the VEX (I think) I need RS-232 (with a RS-232/TTL cable http://www.acroname.com/robotics/parts/R115-INT-BRD-KIT.html) or a TTL-based COM port (which I know I can get from technologics). For gumstix, I would need expansion cards (less than $30) for this. These expansion cards also have USB (mini-B or A connectors). Probably the thumbstix-gs (type-A male USB, 4 TTL serial ports) at $27 is what I would want.

In terms of networking, there is an expansion card for gumstix that allows CF cards. The CF wifi card that I use with Zaurus (a Linksys model) is not listed as supported (according to the article), but I know it has drivers for Linux, since it does work with the Zaurus.

The issue I have is can I stack these expansion cards, allowing me to have two CF slots (one for storage, one for the wifi card)? And also stack these cards with the serial ports and USB? All of a sudden, what was a smallish setup may be much larger, both in terms of size and cost ($120 for the basic board, plus another $120 for the expansion boards, assuming a cost of about $30 each). In the case of the technologics offerings, boards are $179, plus I need to buy a development kit which runs from $150 to $180, depending on the board. This cost would be amortized over the number of robots, however. E.g., if I just buy one board, the robot would be $120 more than a gumstix solution, $60 more if I implement 2 bots, and so on.

I have an e-mail out to the technolgics folks, and I'll probably make some posts at gumstix.org to get answers regarding the stacking of expansion slots. But so far, it's looking like it is down to these two vendors, and the article that I linked at the start of this post helped to confirm that I was on the right track.