The filters add or subtract little from the depth but the sensitivity is #1, more important than Gain IMHO. Gain and Sensitivity go hand in hand but I would rather lower the gain a bit and raise the sensitivity for more stability and depth.
Adjustable recovery speed is important to me and I use 45 in the trash, but too fast RS and I feel that some good targets are missed, especially the deeper ones. That is where I really like the long sweet "round sound" I get with a slower recovery speed. I used the Deus for two months experimenting with depth and recovery speeds and the Deus set to Reactance 0 which is the slowest setting, is still a little faster than the V set at 30. The deep target finds really suffered for me in the last two months. In fact, I would say that I didn't find anything deep with the Deus in my ground and I feel that the recovery speed really hurt me on deep targets.
So, don't be afraid to experiment and use the recovery speed that fits your needs at the time.