I went to K-tech following Chris' recommendation - excellent service. You only have to see how many TT bikes were running K-tech stickers this year to realise that they certainly know their stuff.
I think the main problem with the Evo's suspension, (apart from the fact that it's built down to a budget), is that it runs progressive springs at both ends, which never seem to suit anybody.
If you're not sure about committing to a full suspension upgrade, you could first try just fitting linear rate springs tailored to your weight. Crawford (Crawsue) has resprung his standard shock with an Öhlins spring and dropped some K-tech springs in his forks. You could send him a PM to get his opinion on the results and costs.
I actually tried the Sachs shock with an Öhlins spring and noticed an improvement, even though the spring was firmer than my ideal
http://www.ukmonster.co.uk/monster/s...t=56541&page=3