Since you mention multiple reboots, I just don't know that it is a software incompatibility in your case. I would be very curious to see if you get that same result with a 40MHz or lower clock speed. Because again, my stock 40MHz card doesn't exhibit those hands during boot, perhaps because I have not overclocked the card.
So we either need to underclock Tyler's card to test this. Or we need Equill and a few others to try a high speed (40MHz preferably) Turbo 040 to see their results in the SE/30.
The 1.4MB floppies read/write PROPERLY when the Daystar Turbo 040 is removed, even though a IIfx or IIsi ROM is left in the SE/30. However, since I am using the TS Adapter, I must also mention that removal of the Turbo 040 also requires removal of the TS Adapter. You cannot simply use the TS adapter's top slot to insert a MacCon Ethernet card. You must use it for an accelerator. In other words, the middle slot is mandatory on the TS Adapter, while the top slot is optional.
So simply saying that "it works fine" without the Turbo 040 does not in any way indicate if the problem is the Daystar card or if the problem is the TS Adapter -- since both are being removed.
PowerCache? I wouldn't know. I tried one 50MHz Daystar 030 card which also had 50MHz 68881 co-processor. But as you can see in my Sad Mac photos, I only had crashes with it. I ultimately had to return it to the seller. I think the reason it didn't work in my SE/30 is because it was not the UNIVERSAL version of the 030 card.
What I can say is that the DiiMO 50MHz 030 (with co-processor) works fine with any ROM. No issues with the floppy drive. However, I do not use the TS Adapter along with the DiiMO because the DiiMO doesn't require an adapter like Daystar cards do. But again, this does not necessarily say the TS Adapter is at fault. It still could very well be a Daystar ROM incompatibility with the floppy drive system of the SE/30.