No problem.
From the research I did on a few pond forums and on reefkeeping websites (where I initially heard about them), the reviews have all been very strong. I was worried about reliability too, but out of the box, the pump feels like a quality product; I am happy with mine so far (running strong for 1 year 3 months). There were a few people on pond forums who claimed they have been running theirs for 7+ years with no problems.
There are guys on the reefkeeping sites that run them externally because they are looking to reduce heat transfer into the water, but in my case the extra heat is a benefit so I run mine submerged. Disclaimer: Laguna recommends running them only in submerged applications, but if you run it externally, I have heard that the "click fit" connection is prone to leaking so using a stainless steel hose clamp directly on the discharge is recommended...this fitting is the only bad thing I have to say about the pump...I guess they don't have a threaded discharge that would enable you to plumb directly to PVC so that they can offer you a
threaded "Click fit" connection (sold separately of course

)