Without a doubt, go with the Slee.
I've directly compared SUTs to the Elevator and if you are looking to get to the next level of detail, the Elevator is the way to go. I use the Elevator feeding the Reflex. My LOMCs are a VDH, Yamamoto, and a Soundsmith modified Dynavector.
The SUTs that have been in the system are my Signet which is supposed to use Tamura iron and the K&K Premium. granted, the number of SUTs I've run through the system are limited but both seem to be very well received.
The SUTs sound good but there is a definate veiling compared to the Slee.
,,,just my $.02, YMMV