While not yet finished with the Soviets, there are gaps in the support weapons available to the 20mm German force. This is important because at the level of command/play represented by Spearhead. It's the significance of support weapons, and the player's ability to use combined arms to defeat the opposing player, that represent the biggest appeal of the rules set. I love what call the 'layering' effect that the rules simulate where variety of weapons systems simply yet effectively build 'layers' of effect that cumulatively erode the effectiveness of the opposing force. The system is simple to play yet effective in simulating outcomes (I have always believed that rules sets are either 'means' focused or 'end' focused. Spearhead is 'end' focused.
I reckon that the Moderns set does this best of all because of the greater variety of support weapon options available to a modern army.
So, the other purchase that I made last weekend was a box of HaT German 75mm Infantry Guns. Spearhead OOBs place one stand of these with the regimental support weapons, so generally I won't need more than one or two of these on the table, but ... well ... there were four in the box, and ... I couldn't help myself.
The only downside is that, in my opinion, HaT, these aren't your best work. Here is the PSR review. The crew sculpting is not high quality, and this detracts from the overall quality of the set. However, they are German 75mm IGs, and you still don't see to many other sets of these around, so I'm grateful to HaT for producing them. They will do the job nicely on the table top.