if I buy an ultrasonic cleaner for my records will I be able to hear the difference?

While I echo @cleeds observations regarding convenience for me the real benefit of the us cleaner is how it improves the detail and resolution in LP playback. I used to own VPi and ClearAudio vacuum cleaners and the best thing these did is clear the record. My KL Audio actually changes and improves the sound of the LP, even those that play and appear clean. Whether this benefit is worth it on your system is for you then decide but the investment you make now will pay back as your system improves 

Results will depend on the condition of the record.  Do you buy a lot of used vinyl?

I know you are looking for input from people who own an US cleaner, but that said, cleeds post makes a lot of sense!

(I've ordered the Degritter US cleaner, hopefully to arrive this fall, and I'm really looking forward to trying it out.  It will be my first record cleaner, beyond using an anti-static brush).

I am not sure I can hear the difference between a new record and a US cleaned one.  I have ordered a cheaper US cleaner which I want to use to remove as much as possible the ticks from old second hand records but I am not certain of the results as I am still waiting for delivery of the machine.  To say that US cleaner will improve details and resolution is beyond me.

Short answer:  Yes, you will hear the difference.

Longer answer:  You may not like what you hear.  US isn't magic and it can't do anything for damaged records.  I found that several of my older vinyl copies weren't just dirty after cleaning them with US, they were junk.

On the other hand, the records that were just dirty played, well, not new, but much better.  Some of the rare and rarely played stuff, was simply excellent as compared to pre-US cleaning.

So, you have to make your own decision.  For me, I firmly believe US to be the single greatest advance in vinyl playback improvement since the Discwasher brush.  I think that as long as you stay within whatever you consider to be a reasonable budget, you won't go wrong. I got into mine for < $750 and that worked for me.

Good luck and happy listening no matter which way you go!