Well, yes, when a module has a non-zero mass, there's always a trade-off.
Let's see how much jump range an SLF-capable ship would lose on a cardboard build (from the templates on EDAstro) if they equipped a 5D hangar:
- Alliance Crusader: 0.8 ly - but it's a bad idea, because it'll have too few usable internals
- Anaconda: 2.3 ly - however, it still has a much higher jump range than all the rest
- Beluga: 0.7 ly
- Fed. Corvette: 0.6 ly
- Fed. Gunship: 0.9 ly - but it's also a bad idea
- Imp. Cutter: 0.6 ly
- Keelback: 3.4 ly - but it's also a bad idea
- Krait Mk II: 2.6 ly
- Type-9 Heavy: 0.7 ly
- Type-10 Defender: 0.5 ly
So, in most cases, it hardly matters. In an Anaconda, you'll go from 76 ly to 74 ly: if you plotted a 20k ly route with 98% efficiency, you'd go from 269 jumps to 276 jumps. I suppose the Krait Mk II is the one which loses out the most in a practical setting, as it goes from 62 to 59.6: the same 20k ly route would be up to 343 jumps, from 330.
In other words, unless you're racing or travelling the extreme edge, for both of which you'll want as high a jump range as you can squeeze out, fitting a hangar will make little practical difference when you're travelling.