I also tried filling my stock motor mounts with urethane, still did not work that well for me.. I also tried inserts combined with filled side mounts, along with a torque/engine damper and my motor still moved a ton, enough to cause my WG to hit my hood and dent it

, probably a good 2-4" vertically (spectators said they saw my hood jumping up and down on the driver side at launch
I took it out tonight and DANG they are nice.. a slightly tad bit more vibration that with inserts, but so solid.. I can tell a difference in shifts and especially starting out in first.. no launch abuse yet though..
The only reason I see why you would need these is if:
A: you don't have a front motor mount b/c of turbo placement
AND/OR
B: you are putting down 300+ whp
C: you are a track/strip junkie and have to have the best
For the normal street prelude that has all 4 mounts in place, inserts will do perfectly fine imo..
Aside from fitment/installation problems (minor I guess you could say), these seem to be great mounts.. the lifetime warranty helps too!