It turns out there's a significant improvement to be made to the Silk Road bot, but it isn't to ignore Provinces (when I did that, its win rate plummets). It's to prefer Silk Road to Duchy and to more liberally buy Estates, and only buy Provinces once you have a bunch of golds (5-7). When I do this, the Hoard bot smokes the Monument bot, 65-32.
Revised Hoard bot:
<player name="Hoard/Nomad Camp/Silk Road"
author="mischiefmaker"
description="">
<type name="Province"/>
<type name="TwoPlayer"/>
<type name="SingleCard"/>
<type name="Optimized"/>
<type name="BigMoney"/>
<type name="Bot"/>
<type name="UserCreated"/>
<buy name="Province">
<condition>
<left type="countCardsInDeck" attribute="Gold"/>
<operator type="greaterThan" />
<right type="constant" attribute="7.0"/>
</condition>
</buy>
<buy name="Silk_Road">
<condition>
<left type="countCardsInPlay" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Duchy">
<condition>
<left type="countCardsInPlay" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Estate">
<condition>
<left type="countCardsInPlay" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Hoard">
<condition>
<left type="countCardsInPlay" attribute="Hoard"/>
<operator type="equalTo" />
<right type="constant" attribute="0.0"/>
</condition>
<condition>
<left type="countTurns"/>
<operator type="smallerOrEqualThan" />
<right type="constant" attribute="12.0"/>
</condition>
</buy>
<buy name="Nomad_Camp">
<condition>
<left type="countCardsInDeck" attribute="Nomad_Camp"/>
<operator type="smallerThan" />
<right type="countCardTypeInDeck" attribute="Treasure"/>
<extra_operation type="divideBy" attribute="8.0" />
</condition>
</buy>
<buy name="Silk_Road">
<condition>
<left type="countCardsInDeck" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Duchy">
<condition>
<left type="countCardsInDeck" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Estate">
<condition>
<left type="countCardsInDeck" attribute="Hoard"/>
<operator type="greaterThan" />
<right type="constant" attribute="0.0"/>
</condition>
</buy>
<buy name="Silver"/>
</player>
Ah, but the SP/LH/Steward/Bridge bot still beats it 55-43. So we have an RPS situation, which is pretty interesting all by itself. But also:
Monument-BM, playing from second position, beats Scrying Pool engine 50-47
Scrying Pool engine, playing from second position, beats Silk Road 49-48
Silk Road, playing from second position, beats Monument-BM 59-38
Granted two of those results are so slim they are basically a coin flip, but given that each of these strategies has a unique opening (Monument-Silver, Nomad Camp-Silver, Potion-Steward), you might even make the argument that 2P actually has a very slight advantage here, since he gets to see what his opponent opens.