Now we've been hosted with Clook for about 4 years now and grown from small to large with great support. We have never had any issues with Clook not what we can say about other hosts *cough*.
I can't say how much we would HIGHLY RECOMMEND Clook. They have been fantastic with support every step of the way. Reply within a few minutes and it doesn't matter what time of the day. Early hours or normal working hours they usually solve most cases in a couple of minutes. Upgrades were always seemless and they've always went the extra mile when we've asked extra questions.
They can offer managed or unmanaged. We fit in the middle really and are quite hands on where we can be but have them advising every step of the way.
Based on our growth with Clook we would say they are suitable for any level of customer at any stage of their growth.
I would certainly recommend Clook. One might add they cost slightly more than the average joe host but like anything in life you get what you pay for and with Clook your in safe hands and thats worth its weight in gold for any serious website.