I have a modded Delta, that I won on an ebay auction through Richard Gray of The Power Company fame. The Transport belonged to a friend of his.
This Transport, which I won for $300, had over $600 worth of mods, done by Great Northern Sound in MN. Every Cap was replaced with Blackgates, High Speed Rectifiers, and Bybee Purifiers placed into the incoming AC Path.
Comparing the Unit to my other, bought new in 1997 bone stock Delta (yes I have two of them, I would say the modded Unit has slightly better purity, and smoothness. The differences are subtle, not that startling of a difference.
But, would I say the modded Delta would be worth such an expense to mod? Probably not, and I have to tend to agree with what other posters say, that one would most likely spend thier money much more wisely, by trading up to a better Transport than the Delta.
I will say, they were a nice Transport for the money spentback then, were good, well bulit workhorses, but I would assume there are better to be had, at reasonable prices today.
Had I myself personally ever considered doing any mods to my Delta/Alpha Combo, I'd probably spend the money on the Alpha, modding it instead. Mark