I have had lowering blocks on my bike for over 2 years and have had no problems....I am 235+ and the wife is 180+-, and like somebody said it will firm up the ride some so you will have to get used to that......but other than that they work great.
Which blocks are you using? How much air pressure are you running?
Thanks for sharing your experience.... can I ask which lowering blocks and spacers youb recommend?
I got them off someone on ebay. I think they were about $30 - they came with no spacers and really cheap bolts. So I made the spacers and got new bolts and nylon lock nuts.
I'll be happy to take some pics if you need.
Tom