I do not know where you heard that from, assuming it has DLDI support then it should work.
What you may have heard is that the EZ 3 in 1 aka the EZ5 3 in 1 (it was made for the EZ5 but source code was released and used so most people drop the EZ5 part).
The 3 in 1 on the other hand has ram built into the cart (PSRAM, it is one of the ways the cart works), this ram can be used in some homebrew apps (snesemulDS, quake 1 and 2 (required for 2), not sure about the DS ports of doom, a handful of other apps and ultimately linux). It should work regardless of the DS slot cart you use though.