Yes I agree it will work with cold plain water, but it's main use and what it is really designed for is Central heating systems. Regardless of what they say it will last longer if it has some extra lubricant in the water to "help" the bearings, just like the water-pump on a car engine will last longer with an antifreeze coolant than just plain water in the cars cooling system. Central heating systems use fernox but antifreeze is ok too. I do believe you will be happier with the Eheim, it's light, quite easy to mount, doesn't get hot, and can be easily submerged but don't just take my word for it. Being able to polish a few lumps of metal and dig a large hole doesn't qualify me as an oracle on everything water-cooled
What is your system layout? do you require that huge flow rate? as that may make some differences to the answer?. I stupidly managed to crack the very thin plastic case on my Eheim by using a tapered fitting. It is fixed with araldite and doesn't leak but as such I'm sure you wouldn't want it. I also want to keep it for "emergencies" and a possible mobile box later. Eheims are not excessively priced in the UK my 1250 was about £46 I think, what's the Eheim 1250 price where you are?