Why u don't use resistors?
For ur circuit it's better to use same type MOSFETs (pmos or nmos) otherwise Vref <=> Vdd/2 for different corners. Term "matching" isn't suitable for different type MOSFETs.
Other for different corners current though ur ckt will vary at the least +/-100%.
If Vref is reference for comparator (or other switching ckts), small current though ur circuit can cause unexpected variation of Vref. In this case it's better to increase current (using more strong MOSFETs) or supply Vref though buffer ckt (OTA, AMP).