An 11T smallest cog is an 11T smallest cog no matter what's behind it. There will be absolutely no change in the speed you can get in your top gear.

Again, the Deore and HG50 cassettes provide low gears you have absolutely no need for, they give up useful interior cogs. You said you never use your low gears so why duplicate what you know is useless to you. Go with the Tiagra.