I have a contiguous stern tube with cutless and have had no problems in 2300 hours. Back when mine was first installed, they didn't even have a vent tube, you just had to remember to burp it when you relaunched. I replaced the PSS when I replaced the shaft about 1000 hours ago and now I have a vent tube that just runs up to well above waterline. I was told they stopped making the ventless ones because people kept forgeting to burp them when relaunching.