crap!
likely so. must be that despite being in the t mobile forum,the link you posted first was not really dumped from a t mobile device. the link i posted was from the "non-carrier" (international,i guess?) one section.
i think the phone realizes its not got the stock recovery(tho i wuold have thot it to still work) hence the
security warning
looks like we may need to track down a t mobile specific recovery,still.
hang on a sec and ill try and boot that recovery on my phone.