Do inboard & outboard (dongle) cell modems use same amount of energy?

A recent post-er mentioned that plugging an outboard modem into the Air, runs its battery down a lot.

1.) Is this energy drain the same for built-in modems, and outboard plug-in ones?

2.) Among the plug-in modems sold through cellular providers, how much does battery drain vary? Is there an independent and credible source for comparative info on this?

3.) How does the energy drain of either kind of cellular modem, compare with using the Wi-Fi radio instead?

4.) Do the above answers vary, for 3G vs. 4G?

5.) I'm wondering why Sprint dropped their #301 plug-in modem, the stick-like one. Now they apparently only sell the newer one, shaped like a tiny donut. Does anyone have experience using that one with an Air?

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Sprint does have better pricing, which is attractive. The 3G can run over the cap (like, if 4G hasn't arrived in your area, yet), but the 4G's capless. (Unlike Verizon's upcoming 3/4G service which reportedly is priced the other way around.) Of course Sprint's 4G phone can't run over any data cap anyway, because the battery empties so fast.

Of course if I buy a cell modemless Air and then the new model offers the option of having it built-in, I'll feel stupider than the last Chevy Corvair buyer.

Wirelessly posted (Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 8.12; MSIEMobile6.0) Sprint T7380)

Well, since it's a testable thing, I was hoping someone might have seen a report verifying it.

BTW Sprint had told me their old stick-like 301? modem worked w/ macs. Then I see on recent blogs that -- the round tiny-donut shaped modem being announced as their first one that's Mac-compatible. Yikes! That was a close call, I almost bought the 301. Their pricing can save money, but you really have to watch 'em.