As a design consultant who works with multiple vendors, we have extensive experience with the Mentor, Avanti, and Simplex flows for device level extraction. There are solutions for all of these tools with the Magma environment.
Our recommendation to clients is generally to use whatever is the "gold" device level extraction tool as recommended by your foundry source based on the process technology you are using.
The flow compatibility is not as big an issue as the correlation of the results so the best place to look is to contact your fab and find out their tool and then work with Magma and their partner/vendor to get your flow in place.
Pres. - SiliconMap, LLC
(925) 606-5357 phone
(707) 516-0581 fax