There are very few ops that benefit by sending more than 1 tpa raw. Yes you lose thieves as you send but your success rate will be just as high and you're losses will be easily replaced where as if you use more raw than mods your losses will be harder to replace and you'll fall out of success range more quickly.
Toadi is not talking about running 1 tpa raw and 400% effect in mods rather running 4 tpa raw with 250% effect in mods instead of 6 tpa raw with effect in 166% mods, both have 10 mod tpa but the 4 raw tpa has a much easier time of maintaining 10 mod tpa.