well, I do have an Higher-Range Digital Oscilloscope (Scopemeter) the Hantek DSO1202B.
First off all: If you just want to use it in a lab, you're better off with a Labscope. Well, they do need more space, but the controls are more intuitive and the performance (in the same price-range) is usually better.
The Handhelds are very nice if you need to carry them around (like I do) and can help you a lot. Unless you need the portability I would consider a Handheld scope but not as a "must-have".
I can't tell you anything about the distortion, but I can at least tell you that these Handheld normally have a very slow screen-update-rate and get pretty lazy if you use a high memory option (which some have....like 1M for 1CH/512K for 2CH).
So for finer details on your signal you could use this high memory mode (normally a Labscope starts at 1M
), record a period and check it on the scope (that's what I normally do if I need high res.).
Eventually that is far from a smooth workflow
I would say the UT81B is nice for general checks in rough signals....like putting it in your Toolbag for testing automotive sensors..... but not a High precision Instrument.
Probably you're better off with a used Lab-Scope form ebay. The Rigols are very popular and a lot on the used-market right now.
Another thing: What Signal do you want't to compare your output to? Do you use a Function Generator or some audio-input?