What age or stage was your bubba when you lowered your cot base (assuming you could adjust it of course!)?
I've realised in the last couple of days that my dd can sit by herself for maybe 5 - 10 seconds without tipping over. She can't get herself to sitting yet though and she can't crawl. She is a determined little miss though and super strong & quite tall.
Having said that I have a bad back and the lower position of the cot is quite low, so I am keen to keep her at the higher level as long as it's safe. I didn't have to lower the base for my ds til he was 10 months old when he sat himself up & started to crawl. My dd is only 5 months old!