>>any experience with a small inflatable (mini-liferaft)?<<

Directly, No.

Anything that will get you to the airplane and hold the plane or the pieces while getting you back is good.

If the plane goes down in the brambles on the opposite shore, or if the plane has an APC prop, is your boat going to be transformed into a bubble generator? Zodiacs and Avons are puncture resistant. A wal-mart vinyl pool-toy boat might not be.