The only class I can be somewhat foolhearty with is my Summoner. I often got away with doing the dungeons completely out of order (managing to somehow get to the second continent without even beating half the dungeons or any of the secret dungeons)
Yet saying I love the summoner only greets me with "Ohh yeah of course you love the summon you noob! it is the most broken class ever and liking him only proves your inadequacy" so I never feel good about being good with the summoner.
My suggestion for people using the summoner is that some monsters are much better maxed out then spread out. The difference between a 4 and 5 rank Hydra is as big as night and day. So you either go for 1 level or 5 levels with few exceptions and those exceptions are monsters without dirrect battle application (like Slimes and Turtles)
Summoners are not the most broken class ever. They, like alchemists and, to a lesser extent, necromancers, are very simple to play. Pour points into 1-2 stats, max out a few key skills, and spam the hell out of it. Even compared to, say, archmages, those three classes just spam the hell out of 2-3 options. In the case of summoners, it's more, but most of those are just meat shields. Hydra, Ritch, Flame Drake, Jelly, Turtle are your workhorses. Everything else, for the most part, is there to suck up hits.
So, no. Don't feel bad about liking summoners. They aren't THAT broken. I mean, Oozemancer's and Solipsists exist still. They are just very easy to play.