* mark "Set token1 amount to minimize fees" checked
I would not check this unless you are a kind of Obyte whale. Yeah, the fee will go down but the total payment do opposite. It will go noticeably up because GRD is too expensive. 1GRD ~ $34355 right now. Better to pay the fractions of cent for the fee when you only intention is to buy interest tokens like IUSD, IBIT and IAU.
You can redeem the governance tokens any time and get the GBYTE back, but if you pay the fees then you don't get them at all and you get less interest tokens as well because you are spending your GBYTE on fees. If you are only interested of interest tokens then you should use https://ostable.org/buy page because this will buffer the purchases and will not let you go over 1% in fees.
User may simply lack the fund to pay for GRD when he buying interest tokens. I think the lose of a few cents for fee is not a problem. Just an example if you buy 10 IUSD right now and do not check that box you need to pay ~0.457 Gbyte but if you check it than the sum will be as much 0.91 Gbyte.
Yeah, 10 IUSD is very small amount, which doesn't move the price for IUSD (it effects those coins more that doesn't have so much reserve yet), but like I said, if you are only interested in interest coins then Buy page is more suitable for that https://ostable.org/buy (it accepts GBYTE and other cryptocurrencies too + it doesn't let you accidentally pay too much on fees because it uses buffer).
Buy page even more recommended when you currently buy more than 1000 IUSD because that would mean already 1% of fees, which is already 10 IUSD worth.
If you have "Set token1 amount to minimize fees" checked then you pay double, but you also receive double value too, which you can later sell for profit.