I did use one for my labour with Pip, now sure how it would work with SPD?
Yeah me neither, but I figure some is good, more is better and I can't imagine it would hurt with SPD given you can apparently treat SPD with it as well!
Re DH... ah he did s'thing to his back last year... took 9 months to get better (like PG ha!) - basically a weird combo of some architectural problems (L4 and L5 like to lock-up) then muscle spasms and an inflamed disk (or was it bulging - i forget). So he had about 6 weeks of no lifting last year plus a few more months of minimal lifting (great fun for me - renovations, baby, expressing hmm). Anyway, it finally improved in Dec, so we went... woo hoo lets get PG.. but since then it just keeps flaring up everytime he tries to get fit/do more etc. Physio doesn't know if it's bulging disk now, plus "lots of kilometres on the clock", no cushioning, some osteo-arthritis and seems to get injured at ANYTHING (once he put his back out chopping strawberries!!!!). Basically the physio said rest it as much as possible... (who is supposed to lift the 14kg toddler now!?!?!).... so hence my parents are truly gifts to us (when they're in town), and we're just having to pay ppl to do anything that we cannot do (which seems a lot at present!).

On the bright side... I am MUCH more sympathetic to him than I ever was before (I know really understand how you can overdo it without meaning to) and he is equally sympathetic to me (who has never had significant back/hip problems before). We are a household of heat/icepacks, back massages and physio/osteo/chiro appts lol! And the poor darn dog is getting NO walks whatsoever!