Yes, I have used them. They work quite well, but you have to go at it slowly with the roller, or you generate a load of tiny bubbles. BB
Recently I have varnished my dining table and used mini rollers. The speed of application is very good but I follow with a brush just to quickly get rid of any bubbles or orangepeel. Mrs Painterboy is delighted with the job!
I used Ronseal perfect finish as it came with a paint pad. Used it on the freshly stripped banisters and a wooden beam and it went on fantastically.