As has been widely reported MetroPCS LTE is complementary to T-Mobile's technology: it gives T-Mobile a leg up in LTE in metropolitan areas and the CDMA switch in 2014/15 has already been announced when the spectrum can be repurposed.
Sprint has a large WiMax (also called 4G) user base and WiMax and LTE are less compatible than the various flavours of UMTS based on CDMA and GSM for which SoC already exist. In any case for the network the costs are largely related to upgrading base stations and not handsets as that costs is passed on to the customer. Does anyone know if Sprint still have any of Nextel's completely incompatible iDEN stuff in the network?
T-Mobile's deal is debt free and as the listing will be of MetroPCS lets Deutsche Telekom easily sell equity without losing control. The numbers are clearly on the side of the T-Mobile deal but when has that ever mattered to the telecoms or it-business? Sprint could pursue a bid strategy in an attempt to jack up the price and thus wound a competitor but that would only really benefit the AT&T and Verizon duopoly. If Sprint is looking for a partner it should be looking for one with a nice dowry to help pay down the debt and build out the network. How about tying up with Telmex?