Update to compare the Gitzo 1588 with its successor, the 5540, and their primary competition in my opinion, the Feisol 1471:
Brand Model ........... Max" .. Min" .. Wt-lb Load-lb Sections .. Approx Shipped Price
Gitzo G-1588 .......... 65.0 .. 22.0 ... 2.0 .... 26.5 ..... 4 ......... Discontinued
Gitzo GM-5540 ....... 63.8 .. 21.7 ... 1.9 .... 55 ........ 4 .......... US$315
Feisol CM-1471 ...... 66.9 .. 21.6 ... 1.5 .... 24.2 ..... 4 .......... US$125
Revised pros & cons as between the Feisol and the new Gitzo:
1. Less than half the price of the Gitzo
2. Still noticeably lighter than the Gitzo.
3. Same compacted length almost exactly.
4. At least 3 1/2" extra extension length (as I measured it — more than the specs indicate). For some shooters in the 6'+ height category, this can be a very significant factor. As I mentioned upthread, I ended up having a 3" extension machined for my 5540, while my 1471 fits me just right.
5. Very nice fit and finish. Quality gear.
6. Quick release hand strap.
7. Includes a nice padded bag. (Gitzo now includes a bag, but it's not padded.)
8. Slightly cushier padding on the top section.
Cons (all relative to the Gitzo, not absolute):
1. To my thinking, the new G-locks on the Gitzo have lost some of the the "Mercedes-like quality feel" that I remarked on in the earlier model. But they have done so in trade for the new model's most notable advantage — non-twisting leg sections that make extending and retracting the pod somewhat more convenient, quick and sure than the twisty sections on the 1588 and Feisol.
2. The extra lightness trades off just a bit of solidity and rigidity. Not noticeable with a 1-series and 70-200 f/2.8 on board, but with the 400 f/2.8 loaded I noticed a bit of "twang." Again, only as compared to the ultra-solid Gitzo, and nothing that's not controlled by reasonably good technique anyway. (And not nearly the amount of deflection under the 400 that I noted with the Gitzo 3550. Again, for my own use with the 400 I consider the 3550 unacceptable; the Feisol 1471 is fine.)
3. I mentioned in the OP that the circular platform doesn't come off the Feisol, making for a slightly less elegant QR-clamp installation. This now seems to be equally true of the new Gitzo, so it's now a non-factor (not that it was ever a particularly significant one).
4. The cushier padding of the Feisol still looks like it won't wear as well, but that still remains to be seen. It's holding up fine under fairly light use so far.
5. While I don't entirely credit the new Gitzo load ratings (see my remarks on that upthread), it's true that you must tighten the Feisol sections a little tighter than you might otherwise in the ordinary course of things, or else they will slip under the load of a 400 f/2.8 and 1-series body and arm rested thereupon. Once adequately tightened, however, they hold the load just fine, so I consider this a matter essentially of convenience, not actual capacity.
Bottom line — unless you just want the very best and can live with the height issue, or simply must have the new non-twisting leg sections, the Feisol 1471 is easily the better buy.
Which one do I reach for first? The Gitzo of course. ;-)