Keeping gains is easier than you think. Calculate your new caloric maintenance for your new body weight when coming off cycle. Eat at maintenance and the gains will stay.
Not nesseacairly, everyone's different and if you're way past your natural genetic limit 9/10 times you'll fall back to were you started..or some were around there. The faster and better you recover the more gains you'll keep. But, everyone's different and come can only hold so much whilst others seem to maintain almost everything. This is why blasting and cruising is so much better if you know you're going to be on for awhile..