any handheld for the house is pretty useless... you may get 1 to 2 miles with the HYS 51 inch telescoping antenna from Amazon standing outside depending on your terrain ... with the rubber duck that comes with it you may get a 1/4 mile range.... it's doubtful anyone will be within a mile of your house to talk to...
I have 50 handhelds just about every model ever made... ( I don't have the Uniden pro 538 HH ... first time I've seen it)....
the best is the President Randy II ..
when I buy a new handheld CB that has the SCAN feature on them... I set it on my coffee table with the 51 inch antenna for a few weeks until I get a new one... right now I have a Midland 75-822 on my coffee table... it's an ok hand held...... but EVERY HANDHELD sitting on my coffee table for the last year has yet to hear anyone other than my neighbor when he was playing with his handheld...... other than that..... it stops scanning on channel 6 --- 9 --- and 11... the mega watt super bowl channels... those are the only signals those little handhelds will pick up.
as for on the road use as you said you're going to get a magnet mount antenna... I'm sure you know you can't use a hand held inside a vehicle
I have talked to people that had the little cobra and similar small magnetic antenna's and they barely get a mile... USELESS.... they sell those little antenna's to go with the hand held CB's.... they will talk a mile for the cars in a caravan.... but if you want it to actually work get a good CB antenna... Wilson 1000 mag mount ... Siro performer 5000 with mag mount.... Styker AR-10 ... ... get one that is 60 inches tall and it will do well.... if you can find a discontinued Tram 3500 for cheap money get that one.... any hand held will do fine on a road trip with a decent antenna...... looks like you've been a member since 2010 so you know it's the antenna that receives and transmits... most of the handhelds will work about the same.
I see the Uniden pro 538 HH has FM and the display looks better than the midland... the midland for me is hard to see and when I press the light button it is back lit on two sides but it's a little hard to see the middle of the screen ( mine is older they may have changed them)..
the Uniden pro 538 HH is also cheaper..... I know farpoint farms did a YouTube video on the 75-822 and the little president antenna he likes it.. you can watch it I can't remember the range but I wasn't impressed.... but I know people that have the little president antenna's and it's not worth it for a road trip