Yes, if you simply stop meds altogether (notably beta-blockers) then you can get rebound. However (IME with med-switching) they don't worry about that if you're just being switched to another med. (I have been switched a couple of times; I did see some higher pressures, but this was due to titrating the dose.) If you are going off beta blockers completely and not switching, they prefer to taper.
As a chronic, my understanding is that labetalol is really preferred for obstetric cases because it has a known track record in pregnancy. Several of the drug classes used for HTN are not pregnancy safe. (ACE inhibitors and ARBs are not safe at all, and diuretics are only used with serious caution.) It's not a commonly used drug outside pregnancy.
I have never actually taken labetalol, but it does seem to be shorter acting and thus result in more dips and swings. I took metoprolol ER before and during my second pregnancy and had very consistent pressures.
Aliza - 01/05/2007 - Severe preeclampsia, emergency CS 37 weeks
Isaac - 09/26/2011 - controlled on 150mg Toprol, NO PE, 39 weeks!